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Objective: To investigate the effects of escitalopram, a selective serotonin reuptake inhibitor, on erectile and penile vascular function in the rat., Methods: The effect of chronic treatment with escitalopram (0.286 mg/kg/day) on change in intracavernosal pressure, maximum intracavernosal pressure/mean arterial pressure, and area under the intracavernosal pressure curve in response to cavernosal nerve stimulation was measured. The effect of chronic escitalopram treatment on endothelial-dependent relaxant responses was investigated in isolated mesenteric and internal pudendal resistance arteries. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity and nitric oxide synthase levels were determined with enzymatic assay and Western blot, respectively., Results: Chronic treatment with escitalopram resulted in a significant reduction in the erectile response to cavernosal nerve stimulation without an effect on the response to intracavernosal injection of the nitric oxide donor sodium nitroprusside. The decrease in erectile function was associated with marked increases in NADPH oxidase activity in the corpora cavernosa. Treatment with escitalopram also caused a significant reduction in the relaxant response to acetylcholine in isolated internal pudendal and mesenteric resistance arteries without altering the response to sodium nitroprusside. The decreased response to acetylcholine in the isolated vascular segments was associated with a marked increase in NADPH oxidase activity that was corrected by treatment with the NAPDH oxidase inhibitor apocynin., Conclusion: The inhibitory effects of escitalopram on erectile and vascular function were not accompanied by a change in endothelial nitric oxide synthase, neuronal nitric oxide synthase, inducible nitric oxide synthase expression, or endothelial nitric oxide synthase activity, suggesting that the inhibitory effect is caused by a decrease in nitric oxide bioavailability mediated by increased NADPH oxidase and reactive oxygen species production., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Congestive heart failure is the leading cause of hospitalizations for patients older than 65 years. There are almost 700,000 new cases of heart failure annually and re-hospitalization rates are as high as 50% within the first few months of initial discharge. These statistics translate to healthcare costs that nearly reached US$40 billion in 2010. Understanding the therapeutic agents that can not only help decrease mortality and morbidity but also decrease the rate of re-hospitalizations is vital in the management of congestive heart failure. Here, the authors highlight the various classes of drugs used in the treatment of heart failure. They then provide a focused review examining the multiple clinical trials that have emphasized the evaluation of mortality, morbidity and hospitalization rates in heart failure patients who are receiving the different types of therapeutic agents.

Objective: To evaluate the effect of the tyrosine kinase inhibitor imatinib mesylate (Gleevec) on human corpus cavernosum (HCC) smooth muscle tone., Methods: HCC were obtained from 18 erectile dysfunction (ED) patients undergoing penile prosthesis surgery. The effects of imatinib in HCC strips were investigated in the presence of various inhibitors. The human phosphoreceptor protein tyrosine kinase (PTK) array (Proteome Profiler Array) detected changes in receptor phosphorylation before and after imatinib. Immunohistochemistry was used to localize phosphorylated c-kit (CD117/stem cell factor) in HCC smooth muscle cells., Results: Phenylephrine-induced contraction in HCC was significantly inhibited by imatinib (97.7% ± 2.3%). l-nitro-arginine methyl ester (l-NAME) or guanylyl cyclase inhibitor [1H-1,2,4] oxadiazolo [4,3-a]quinoxalin-1-one (ODQ) alone did not reverse the effect of imatinib, but suppressed this response in combination (18.0% ± 0.6%). The K(+) channel blockers (apamin and tetraethyl ammonium) decreased the imatinib-induced relaxation by 64% and 51%, respectively. PTK microarray analysis of 42 different phospho-receptor tyrosine kinases showed 14 were clearly activated in HCC. Imatinib treatment significantly inhibited phosphorylation of PTKs. A high level of CD117/c-kit-positive immunostaining was detected in untreated HCC smooth muscle, but not in treated HCC., Conclusion: Imatinib caused HCC smooth muscle relaxation in vitro mediated by nitric oxide/guanosine monophosphate signaling, involving the large-conductance Ca(2+)-activated K(+)-channels (BK(Ca)) or by inhibiting the upregulated PTK pathway. These results suggest that imatinib may also benefit erectile dysfunction patients who are not responsive to phosphodiesterase-5 inhibitors., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Nitric oxide (NO) is the principal mediator of penile erection, and PDE-5 inhibitors are the first-line agents used to treat erectile dysfunction (ED). When NO formation or bioavailability is decreased by oxidative stress and PDE-5 inhibitors are no longer effective, a new class of agents called soluble guanylate cyclase (sGC) stimulators like BAY 41-8543 will induce erection. sGC stimulators bind to the normally reduced, NO-sensitive form of sGC to increase cGMP formation and promote erection. The sGC stimulators produce normal erectile responses when NO formation is inhibited and the nerves innervating the corpora cavernosa are damaged. However, with severe oxidative stress, the heme iron on sGC can be oxidized, rendering the enzyme unresponsive to NO or sGC stimulators. In this pathophysiological situation, another newly developed class of agents called sGC activators can increase the catalytic activity of the oxidized enzyme, increase cGMP formation, and promote erection. The use of newer agents that stimulate or activate sGC to promote erection and treat ED is discussed in this brief review article.

Objective: To investigate the erectile and cardiovascular responses to the tyrosine kinase inhibitor imatinib in the rat., Materials and Methods: The effect of intracavernosal injection of imatinib on the intracavernosal pressure (ICP), ICP/mean arterial pressure (MAP) ratio, area under the curve, and duration of the increase in ICP and the effect of intravenous injection of imatinib on the MAP, cardiac output, and total peripheral resistance were investigated. The effect of the nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester on the responses to imatinib was investigated., Results: Intracavernosal injection of imatinib produced significant dose-related increases in the ICP, ICP/MAP ratio, area under the curve, and duration of the increase in ICP and decreases in the MAP. The erectile responses to imatinib were rapid in onset and short in duration. The erectile responses to imatinib were not significantly altered by NG-nitro-L-arginine methyl ester or cavernosal nerve crush injury, and imatinib was significantly less potent than the nitric oxide donor sodium nitroprusside in inducing erection. Intravenous injection of imatinib produced significant dose-related decreases in the MAP without significantly changing the cardiac output, and imatinib was significantly less potent than sodium nitroprusside in decreasing the MAP. Systemic vascular resistance was decreased in a significant dose-related manner, and the vasodilator responses to imatinib were not altered by NG-nitro-L-arginine methyl ester., Conclusion: The present results have indicated that imatinib has significant erectile and systemic vasodilator activity in the rat that is not dependent on nitric oxide release. Another tyrosine kinase inhibitor, nilotinib, also increased the ICP and decreased the MAP in the rat. These data suggest that tyrosine kinases might play a constitutive role in maintaining penile tumescence and the baseline vasoconstrictor tone in the peripheral vascular bed., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Nitric oxide (NO) is the principal mediator of penile erection, and soluble guanylate cyclase (sGC) is the receptor for NO. In pathophysiological conditions when sGC is inactivated and not responsive to NO or sGC stimulators a new class of agents called sGC activators increase the activity of NO-insensitive sGC and produce erection. The aim of this study was to investigate erectile responses to BAY 60-2770, a sGC activator, under physiological and pathophysiological conditions. In the present study increases in intracavernosal pressure (ICP) in response to intracavernosal (ic) injections of BAY 60-2770 were investigated under baseline conditions, when sGC was inhibited by 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), when nitric oxide synthase (NOS) was inhibited by N-nitro-L-arginine methyl ester (L-NAME), and after cavernosal nerve crush injury. Under baseline conditions ic injections of BAY 60-2770 increase ICP, ICP/mean arterial pressure (MAP), and area under the ICP curve (AUC) and produce small decreases in MAP at the highest doses studied. BAY 60-2770 was very potent in its ability to induce erection and responses to BAY 60-2770 were enhanced by ODQ which attenuates erectile responses to sodium nitroprusside (SNP), diethylamine NONOate (DEA/NO), and cavernosal nerve stimulation. Responses to BAY 60-2770 were not altered by L-NAME or cavernosal nerve crush injury. These data indicate that BAY 60-2770 has potent erectile activity that is enhanced by ODQ and show that responses to BAY 60-2770 are not attenuated by NOS inhibition or cavernosal nerve injury. These results suggest that BAY 60-2770 would be effective in the treatment of erectile dysfunction when NO bioavailability is reduced, after pelvic nerve injury, and when sGC is oxidized.

Introduction: Soluble guanylate cyclase (sGC) is the receptor for nitric oxide (NO) and in pathophysiologic conditions where NO formation or bioavailability is impaired, erectile dysfunction (ED) occurs., Aim: The aim of this study was to investigate erectile responses to the sGC stimulator BAY 41-8543 in physiologic and pathophysiologic conditions., Methods: Increases in intracavernosal pressure (ICP) in response to intracavernosal (ic) injections of BAY 41-8543 were investigated in the anesthetized rat., Main Outcome Measures: Increases in ICP/MAP in response to ic injections of BAY 41-8543 and the interaction of BAY 41-8543 with exogenous and endogenously released NO were investigated and the effect of the sGC stimulator on cavernosal nerve injury was assessed. The mechanism of the increase in ICP/MAP in response to ic injection of acetylcholine was investigated., Results: The ic injections of BAY 41-8543 increased ICP/MAP and the duration of the response. BAY 41-8543 was less potent than sodium nitroprusside (SNP) and ic injections of BAY 41-8543 and SNP produced a larger response than the algebraic sum of responses to either agent alone. Simultaneous ic injection of BAY 41-8543 and cavernosal nerve stimulation produced a greater response than either intervention alone. Atropine and cavernosal nerve crush injury decreased the response to nerve stimulation and ic injection of BAY 41-8543 restored the response., Conclusion: These data show that BAY 41-8543 has significant erectile activity and can synergize with exogenous and endogenously released NO. This study shows that atropine and nerve crush attenuate the response to cavernosal nerve stimulation and that BAY 41-8543 can restore the response. The results with atropine, L-NAME and hexamethonium indicate that the response to ic injection of acetylcholine is mediated by muscarinic receptors and the release of NO with no significant role for nicotinic receptors. These results suggest that BAY 41-8543 would be useful in the treatment of ED., (© 2012 International Society for Sexual Medicine.)

Nitric oxide is a potent vasodilator that plays a critical role in disorders of erythrocyte function. Sickle cell disease, paroxysmal nocturnal hemoglobinuria and banked blood preservation are three conditions where nitric oxide is intimately related to dysfunctional erythrocytes. These conditions are accompanied by hemolysis, thrombosis and vasoocclusion. Our understanding of the interaction between nitric oxide, hemoglobin, and the vasculature is constantly evolving, and by defining this role we can better direct trials aimed at improving the treatments of disorders of erythrocyte function. Here we briefly discuss nitric oxide's interaction with hemoglobin through the hypothesis regarding Snitrosohemoglobin, deoxyhemoglobin, and myoglobin as nitrite reductases. We then review the current understanding of the role of nitric oxide in sickle cell disease, paroxysmal nocturnal hemoglobinuria, and banked blood, and discuss therapeutics in development to target nitric oxide in the treatment of some of these disorders.

Background: Soluble guanylyl cyclase (sGC) is expressed in mammalian cytoplasm and catalyzes the synthesis of the second messenger guanosine 3',5'-monophosphate (cGMP) involved in important physiological functions such as relaxation of vascular smooth muscle, inhibition of platelet aggregation, modulation of inflammation, and control of vascular permeability. sGC is the intracellular receptor for nitric oxide (NO) and the active moiety in traditional organic nitrate therapy, recently as an inhalant in the intensive care unit and experimentally in improving microcirculatory flow in shock. However, dysfunction of the heme moiety on sGC occurs in a number of cardiovascular diseases, which reduces NO effectiveness., Methods: In this review, we examine animal studies and early clinical trials on agents that can directly stimulate sGC and may have future clinical application in cardiovascular disease and in perioperative care., Conclusions: Animal and early clinical studies have shown that sGC stimulator agents have great promise for treating cardiopulmonary disorders and may also have a role in modulating the inflammatory response observed in perioperative care.

Phosphodiesterase-5 inhibitors (PDE5i, sildenafil, vardenafil, tadalafil and avanafil) are a first-line medical therapy for erectile dysfunction (ED). In all likelihood, PDE5i usage will increase because sildenafil (Viagra® and Revatio®) and tadalafil (Cialis® and Adcirca®) have recently been recommended as first-line therapy for patients with pulmonary hypertension (PH). PDE5i exhibit higher plasma concentrations when co-administered with cytochrome P (CYP) 3A inhibitors, which influences their side-effect profile. The higher PDE5i plasma concentrations, caused by CYP3A inhibitors, influence the severity and timing of PDE5i drug interactions and require dose adjustment. PDE5i are safe when used with most antihypertensive agents, but co-administration with nitrates or α-blockers can cause severe hypotension and syncope. Dose adjustment is also necessary when PDE5i are co-administered with CYP3A inducers. The combination of oral tadalafil and bosentan (endothelin receptor antagonist) reduces tadalafil levels and requires dose adjustment. Current literature reports a number of interactions between PDE5i and other agents and further studies are needed to expand our knowledge base of these interactions. This review discusses relevant PDE5i drug interactions, including those with CYP 450 inhibitors and inducers which are frequently used during the treatment of ED and PH.

Objective: To investigate the effects of the selective Rho-associated protein kinase (ROCK) inhibitor azaindole-1 on erectile function under physiologic and pathophysiologic conditions in the rat., Methods: The effect of intracavernosal (i.c.) injections of azaindole-1 on change in intracavernous pressure (ICP), ICP/mean arterial pressure (MAP), area under the curve (AUC), and response duration were investigated in the anesthetized rat under control conditions and when nonadrenergic noncholinergic neurotransmission and cholinergic function or soluble guanylyl cyclase (sGC) were inhibited or after cavernosal nerve crush injury., Results: The i.c. injections of azaindole-1 produced dose-related increases in ICP/MAP and AUC that were long-lasting at the highest doses studied compared with the prototypical ROCK inhibitor fasudil. Erectile responses were not altered by 7-nitroindazole and atropine in doses that reduced the response to cavernosal nerve stimulation by 86%, indicating that they were independent of NO release by cavernosal nerves or activation of muscarinic receptors in the corpora cavernosa. Erectile responses to azaindole-1 were not altered by the sGC inhibitor ODQ in a dose that attenuated responses to the NO donor sodium nitroprusside, indicating that they were independent of an action on sGC. The erectile response to i.c. injections of azaindole-1 or Y-27632, which was reported to be NO/cyclic guanosine monophosphate-dependent, was not attenuated after cavernosal nerve crush injury., Conclusion: The present studies indicate that azaindole-1 has long-lasting erectile activity that is independent of NO release, muscarinic receptor, or sGC activation or the integrity of the cavernosal nerves., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Introduction: Treatment with 5-alpha reductase inhibitors (5ARI) is commonly utilized for the treatment of benign prostatic hyperplasia (BPH). The true prevalence of sexual side effects with 5ARI treatment is currently unknown., Areas Covered: The current article reviews the reported adverse effects of 5ARI in regard to erectile function, sexual desire and ejaculation. A PubMed search was performed of all articles from 1990 to present, which reported any sexual side effects with finasteride or dutasteride. Preference was given to more recent and human studies where available., Expert Opinion: Clinical trials with 5ARI report prevalence rates of de novo erectile dysfunction of 5 - 9%. Decreased circulating dihydrotestosterone (DHT) resulting from 5ARI use is associated with diminished sexual desire and/or orgasm. The presence of adverse sexual effects is associated with decreased self-esteem, quality of life and ability to maintain an intimate relationship. Inhibition of 5ARI additionally influences progesterone and deoxycorticosterone levels and may alter psychological functions, including increased depression, melancholy and loss of general well being. Ejaculatory dysfunction has not been well studied in patients using 5ARI. Patients receiving therapy with 5ARI should be counseled as to potential sexual and psychological adverse effects. Future clinical studies are needed to further investigate the sexual side effects associated with this class of drugs.

Objective: We compared the effect of the long acting basal insulin analog detemir with neutral protamine Hagedorn (NPH) insulin, and normal saline on recovery from vascular injury (balloon catheter mediated) in an animal model of insulin resistance., Methods: Female Zucker fatty rats were administered NPH/detemir/saline for 7 days following which, they underwent balloon catheter mediated injury of left carotid artery, and were continued on the respective regimen for an additional 21 days when they were sacrificed. We evaluated the injured carotid artery for intimal hyperplasia (Intima/Media ratio) and also, aortic arch protein for markers of oxidative stress and inflammation, in addition to expression and phosphorylation of eNOS using well established methods., Results: There was a significant difference in intimal hyperplasia (Intima/Media ratio) between control and detemir treated rats (1.3±0.09, 0.82±0.08; p<0.001) whereas the IM ratio in NPH treated rats was not significantly different from saline (1.17±0.1). Expression of p-eNOS (ser-1177) in both NPH and insulin detemir (1.3±0.15, 1.11±0.12) was significantly higher than controls (0.56±0.13; p<0.05). We did not find significant differences in the expression of MnSOD, eNOS and NFκB-p65., Conclusion: We conclude that in insulin resistant states, treatment with Insulin detemir but not NPH is associated with less intimal hyperplasia, although both insulins increased eNOS phosphorylation., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Epidemiological studies have consistently linked inhalation of particulate matter (PM) to increased cardiac morbidity and mortality, especially in at risk populations. However, few studies have examined the effect of PM on baseline cardiac function in otherwise healthy individuals. In addition, airborne PM contain environmentally persistent free radicals (EPFR) capable of redox cycling in biological systems. The purpose of this study was to determine whether nose-only inhalation of EPFRs (20 min/day for 7 days) could decrease baseline left ventricular function in healthy male Sprague-Dawley rats. The model EPFR tested was 1,2-dichlorobenzene chemisorbed to 0.2-μm-diameter silica/CuO particles at 230°C (DCB230). Inhalation of vehicle or silica particles served as controls. Twenty-four hours after the last exposure, rats were anesthetized (isoflurane) and ventilated (3 l/min), and left ventricular function was assessed using pressure-volume catheters. Compared with controls, inhalation of DCB230 significantly decreased baseline stroke volume, cardiac output, and stroke work. End-diastolic volume and end-diastolic pressure were also significantly reduced; however, ventricular contractility and relaxation were not changed. DCB230 also significantly increased pulmonary arterial pressure and produced hyperplasia in small pulmonary arteries. Plasma levels of C-reactive protein were significantly increased by exposure to DCB230, as were levels of heme oxygenase-1 and SOD2 in the left ventricle. Together, these data show that inhalation of EPFRs, but not silica particles, decreases baseline cardiac function in healthy rats by decreasing cardiac filling, secondary to increased pulmonary resistance. These EPFRs also produced systemic inflammation and increased oxidative stress markers in the left ventricle.

Unlabelled: What's known on the subject? and What does the study add? In the present study the mechanisms regulating EFS-evoked neurogenic contraction in the human corpus cavernosum (HCC) were investigated. Overall, our data adds to current knowledge that the NO-independent heme dependent activation of sGC and the RhoA/Rho-kinase signaling pathways play an important role in the regulation of neurogenic contractile activity in HCC tissue., Objective: To investigate the mechanisms of adrenergically mediated smooth muscle contraction in the human corpus cavernosum (HCC) using an organ bath approach., Methods: Human corpus cavernosum specimens were obtained from patients (aged 59-72 years) with erectile dysfunction (ED), undergoing penile prosthesis implantation surgery. Isolated HCC strips (1 × 1 × 6 mm) were suspended in tissue bath chambers for isometric tension recording. The effects of various drugs on neurogenic contractions evoked by electrical field stimulation (EFS) were investigated. The drugs included nitric oxide (NO) donors, phosphodiesterase 5 (PDE5) inhibitor, Rho kinase (ROCK) inhibitor, NO-independent stimulator, L-type Ca2+ channel blocker and α-receptor antagonist., Results: Pre-incubation with the NO donor sodium nitroprusside (SNP; 10(4) M) significantly reduced the initial peak increase in tension evoked by EFS (by 71%, P < 0.05). The PDE5 inhibitor sildenafil (10(-4) M) reduced the increase in tension by 69%, while a combination of sildenafil and ROCK inhibitor, fasudil, inhibited tension by 81%. The EFS-induced contractile response at 80 Hz was decreased by 65% with fasudil and by 70% with isradipine (P < 0.001), while a combination of these drugs decreased the response by 88%. An NO-independent stimulator soluble guanylate cyclase (sGC), BAY 41-8543, significantly reduced the response (by 82%, P < 0.001) Phentolamine, an α-receptor antagonist, nearly eliminated the contractile response (98%, P < 0.001)., Conclusions: These data suggest that neurogenic contractions are mediated by an increase in Ca(2+) influx via L-type voltage-gated Ca(2+) channels and that an increase in Ca(2+) sensitivity is mediated by the ROCK pathway and the PDE5 enzyme system as well as by the inhibitory NO/sGC/cGMP pathway. The neurogenic contractile response in HCC is mediated by several intracellular pathways, including adrenergic receptors, Ca(2+) entry, Ca(2+) sensitization and activation of the PDE5 enzyme. The Rho-kinase (ROCK) inhibitor fasudil, L-type Ca(2+) channel antagonist isradipine, and PDE5 inhibitor sildenafil, as well as a NO-independent stimulator of sGC, had similar inhibitory effects, suggesting parallel mechanisms in the HCC., (© 2012 BJU INTERNATIONAL.)

Responses to a selective azaindole-based Rho kinase (ROCK) inhibitor (azaindole-1) were investigated in the rat. Intravenous injections of azaindole-1 (10-300 µg/kg), produced small decreases in pulmonary arterial pressure and larger decreases in systemic arterial pressure without changing cardiac output. Responses to azaindole-1 were slow in onset and long in duration. When baseline pulmonary vascular tone was increased with U46619 or L-NAME, the decreases in pulmonary arterial pressure in response to the ROCK inhibitor were increased. The ROCK inhibitor attenuated the increase in pulmonary arterial pressure in response to ventilatory hypoxia. Azaindole-1 decreased pulmonary and systemic arterial pressures in rats with monocrotaline-induced pulmonary hypertension. These results show that azaindole-1 has significant vasodilator activity in the pulmonary and systemic vascular beds and that responses are larger, slower in onset, and longer in duration when compared with the prototypical agent fasudil. Azaindole-1 reversed hypoxic pulmonary vasoconstriction and decreased pulmonary and systemic arterial pressures in a similar manner in rats with monocrotaline-induced pulmonary hypertension. These data suggest that ROCK is involved in regulating baseline tone in the pulmonary and systemic vascular beds, and that ROCK inhibition will promote vasodilation when tone is increased by diverse stimuli including treatment with monocrotaline.

Pulmonary hypertension (PH) is a rare disorder that without treatment is progressive and often fatal within 3 years. The treatment of PH involves the use of a diverse group of drugs and lung transplantation. Although nitrite was once thought to be an inactive metabolite of endothelial-derived nitric oxide (NO), there is increasing evidence that nitrite may be useful in the treatment of PH, but the mechanism by which nitrite exerts its beneficial effect remains uncertain. The purpose of this study was to investigate the effect of chronic sodium nitrite treatment in a PH model in the rat. Following induction of PH with a single injection of monocrotaline, 60 mg; daily ip injections of sodium nitrite (3mg/kg) starting on day 14 and continuing for 21 days, resulted in a significantly lower pulmonary arterial pressure on day 35 when compared to values in untreated animals with monocrotaline-induced PH. In monocrotaline-treated rats, daily treatment with ip nitrite injections for 21 days decreased right ventricular mass and pathologic changes in small pulmonary arteries. Nitrite therapy did not change systemic arterial pressure or cardiac output when values were measured on day 35. The decreases in pulmonary arterial pressure in response to iv injections of sodium nitroprusside, sodium nitrite, and BAY 41-8543 were not different in rats with monocrotaline-induced pulmonary hypertension and rats with chronic nitrite therapy when compared to responses in animals in which pulmonary arterial pressure was increased with U46619. These findings are consistent with the hypothesis that the mechanisms that convert nitrite to vasoactive NO, activate soluble guanylyl cyclase and mediate the vasodilator response to NO or an NO derivative are not impaired. The present data are consistent with the results of a previous study in monocrotaline-induced PH in which systemic arterial pressure and cardiac output were not evaluated and are consistent with the hypothesis that nitrite is effective in the treatment of monocrotaline-induced PH in the rodent., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Responses to glyceryl trinitrate/nitroglycerin (GTN), S-nitrosoglutathione (GSNO), and sodium nitrite were compared in the intact chest rat. The iv injections of GTN, sodium nitrite, and GSNO produced dose-dependent decreases in pulmonary and systemic arterial pressures. In as much as cardiac output was not reduced, the decreases in pulmonary and systemic arterial pressures indicate that GTN, sodium nitrite, and GSNO have significant vasodilator activity in the pulmonary and systemic vascular beds in the rat. Responses to GTN were attenuated by cyanamide, but not allopurinol, whereas responses to nitrite formed by the metabolism of GTN were attenuated by allopurinol and cyanamide. The results with allopurinol and cyanamide suggest that only mitochondrial aldehyde dehydrogenase is involved in the bioactivation of GTN, sodium nitrite, and GSNO, whereas both pathways are involved in the bioactivation of nitrite anion in the intact rat. The comparison of vasodilator activity indicates that GSNO and GTN are more than 1000-fold more potent than sodium nitrite in decreasing pulmonary and systemic arterial pressures in the rat. Following administration of 1H-[1,2,4]-oxadizaolo[4,3-]quinoxaline-1-one (ODQ), responses to GTN were significantly attenuated, indicating that responses are mediated by the activation of soluble guanylyl cyclase. These data suggest that the reduction of nitrite to nitric oxide formed from the metabolism of GTN, cannot account for the vasodilator activity of GTN in the intact rat and that another mechanism; perhaps the formation of an S-NO, may mediate the vasodilator response to GTN in this species., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Peroxynitrite (PN) worsens pathological conditions associated with oxidative stress. However, beneficial effects have also been reported. PN has been shown to demonstrate vasodilator as well as vasoconstrictor properties that are dependent upon the experimental conditions and the vascular bed studied. PN-induced vascular smooth muscle relaxation may involve the formation of nitric oxide (NO) donors. The present results show that PN has significant vasodilator activity in the pulmonary and systemic vascular beds, and that responses to PN were not attenuated by L-penicillamine (L-PEN), a PN scavenger, whereas responses to sodium nitroprusside (SNP) were decreased. PN had a small inhibitory effect on decreases in arterial pressure in response to the NO donors diethylammonium (Z)-1-(N,N-diethylamino)diazen-1-ium-1,2-diolate (DEA/NO) and S-nitrosoglutathione (GSNO). PN partially reversed hypoxic pulmonary vasoconstriction. PN responses were attenuated by the soluble guanylate cyclase (sGC) inhibitor, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) and responses to PN and the PN precursor, 3-morpholinosydnonimine (SIN-1), were different. These data show that PN has potent pulmonary vasodilator activity in the rat, and provide evidence that a PN interaction with S-nitrosothiols is not the major mechanism mediating the response. These data suggest that responses to PN are mediated by the activation of sGC, and that PN has a small inhibitory effect on NO responses.

Tissue resident mesenchymal stem cells (MSCs) are known to participate in tissue regeneration that follows cell turnover, apoptosis, or necrosis. It has been long known that aging impedes an organism's repair/regeneration capabilities. In order to study the age associated changes, the molecular characteristics of adipose tissue derived MSCs (ASCs) from three age groups of healthy volunteers, i.e., young, middle aged, and aged were investigated. The number and multilineage differentiation potential of ASCs declined with age. Aging reduces the proliferative capacity along with increases in cellular senescence. A significant increase in quiescence of G2 and S phase was observed in ASCs from aged donors. The expression of genes related to senescence such as CHEK1 and cyclin-dependent kinase inhibitor p16(ink4a) was increased with age, however genes of apoptosis were downregulated. Further, an age-dependent abnormality in the expression of DNA break repair genes was observed. Global microRNA analysis revealed an abnormal expression of mir-27b, mir-106a, mir-199a, and let-7. In ubiquitously distributed adipose tissue (and ASCs), aging brings about important alterations, which might be critical for tissue regeneration and homeostasis. Our findings therefore provide a better understanding of the mechanism(s) involved in stem cell aging and regenerative potential, and this in turn may affect tissue repair that declines with aging., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Porcine small intestinal submucosa (SIS) has been widely used in tunica albuginea (TA) reconstructive surgery. Adipose tissue-derived stem cells (ADSCs) can repair damaged tissue, augment cellular differentiation, and stimulate release of multiple growth factors. The aim of this rat study was to assess the feasibility of seeding ADSCs onto SIS grafts for TA reconstruction. Here, we demonstrate that seeding syngeneic ADSCs onto SIS grafts (SIS-ADSC) resulted in significant cavernosal tissue preservation and maintained erectile responses, similar to controls, in a rat model of bilateral incision of TA, compared with sham-operated animals and rats grafted with SIS graft (SIS) alone. In addition to increased TGF-β1 and FGF-2 expression levels, cross-sectional studies of the rat penis with SIS and SIS-ADSC revealed mild to moderate fibrosis and an increase of 30% and 40% in mean diameter in flaccid and erectile states, respectively. SIS grafting induced transcriptional up-regulation of iNOS and down-regulation of endothelial NOS, neuronal NOS, and VEGF, an effect that was restored by seeding ADCSs on the SIS graft. Taken together, these data show that rats undergoing TA incision with autologous SIS-ADSC grafts maintained better erectile function compared with animals grafted with SIS alone. This study suggests that SIS-ADSC grafting can be successfully used for TA reconstruction procedures and can restore erectile function.

With the increasing awareness of Peyronie's disease (PD), the interest in new concept medications to treat the disorder is escalating. Profibrogenic factors such as transforming growth factor (TGF)-beta1, endothelin (ET-1), connective tissue growth factor (CTGF), angiotensin (Ang) II and platelet derived growth factor (PDGF), all appear to be involved in the pathogenesis of PD. β-Thymosins, pirfenidone, nitric oxide (NO) donors, phosphodiesterase (PDE)-5 inhibitors, matrix metalloproteinases (MMPs)/anti-tissue inhibitor of metalloproteinases (TIMP)-1 reduce collagen synthesis, while decorin, follistatin, and Smad 7 exert antifibrotic effects; all have been proposed for the treatment of PD. Alternative and/or novel approaches for the treatment of PD are needed in part because of the recognized multifactorial etiology of this complex disorder. A comprehensive approach for translating available experimental information into clinically effective drug trials for the treatment of PD is needed. We propose a multi-faceted approach for drug development to generate novel drug products for the treatment of PD., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Phosphodiesterase (PDE) enzymes are widely distributed throughout the body, having numerous effects and functions. The use of on demand PDE5 inhibitors (-Is) for the treatment of erectile dysfunction (ED) has recently obtained approval for chronic daily dosing for the same indication. There are published data supporting the use of PDE5-Is for the treatment of lower urinary tract symptoms (LUTS) caused by benign prostatic hyperplasia (BPH). Additional reports suggest benefit by these agents in patients with chronic heart failure, pulmonary hypertension, essential hypertension, and for the treatment of ischemia. Various central nervous system disorders have been described as targets by PDE5-Is. Sildenafil may have a potential therapeutic indication as a cognitive enhancer in age-related cerebral conditions. There is preclinical evidence for further investigation of the use of PDE5A -Is to improve recovery of cerebral function in humans after stroke by enhancing angiogenesis, neurogenesis and improving neurologic function. Sildenafil delays intestinal ulceration by an increase in the secretion of mucus/fluid and a decrease in hypermotility, and has a protective effect in reducing gastric damage. Larger scale, well designed clinical trials are needed to ascertain the safety, efficacy and cost-effectiveness of PDE5-Is in the future treatment of both urologic and non-urologic diseases. In this review, potential applications of PDE5-Is on urologic, cardiovascular, gastrointestinal, and central nervous system disorders will be updated.

Pulmonary arterial hypertension is a disease characterized by a sustained increase in pulmonary arterial pressure leading to right heart failure. Current treatments focus on endothelial dysfunction and an aberrant regulatory pathway for vascular tone. Unfortunately, a large proportion of patients are unresponsive to conventional vasodilator therapy. Investigations are ongoing into the effects of experimental therapies targeting the signal transduction pathway that mediates vasodilation. Here, we briefly discuss the pathophysiology of pulmonary hypertension and endothelial dysfunction, along with current treatments. We then present a focused review of recent animal studies and human trials examining the use of activators and stimulators of soluble guanylate cyclase for the treatment of pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension.

Introduction: Rho-kinase (ROCK) is a serine/threonine kinase and is one of the major downstream effectors of the small guanosine triphosphatase Rho. In the past few years, evidence has been accumulating to suggest that the RhoA/ROCK system may play an important role in the pathogenesis of a number of cardiovascular and urogenital disorders., Aim: The aim of this study is to review the literature pertaining to the role of the RhoA/ROCK system in male urogenital function., Methods: Comprehensive literature review was performed using PubMed., Main Outcome Measures: Inhibitors of ROCK may have potential therapeutic applications, as derived from preclinical and a few clinical studies., Results: Published reports suggest that elevated RhoA/Rho-kinase signaling plays a role in the development of benign prostatic hyperplasia, erectile dysfunction, kidney failure, ejaculation disorders, prostate and bladder cancer initiation, and eventual metastasis., Conclusions: This review focuses on our current understanding of the role of the RhoA/Rho-kinase pathway in the regulation of the male urogenital system. Rho-kinase inhibitors may evolve into an important pharmacologic option in the future treatment of urogenital system disorders., (© 2010 International Society for Sexual Medicine.)

4-({(4-Carboxybutyl)[2-(5-fluoro-2-{[4'-(trifluoromethyl)biphenyl-4-yl]methoxy}phenyl)ethyl]amino}methyl)benzoic acid (BAY 60-2770) is a nitric oxide (NO)-independent activator of soluble guanylyl cyclase (sGC) that increases the catalytic activity of the heme-oxidized or heme-free form of the enzyme. In this study, responses to intravenous injections of the sGC activator BAY 60-2770 were investigated under baseline and elevated tone conditions induced by the thromboxane mimic U-46619 when NO synthesis was inhibited by N(ω)-nitro-L-arginine methyl ester hydrochloride (L-NAME), when sGC activity was inhibited by 1H-[1,2,4]-oxadizaolo[4,3]quinoxaline-1-one (ODQ), an agent that oxidizes sGC, and in animals with monocrotaline-induced pulmonary hypertension. The intravenous injections of BAY 60-2770 under baseline conditions caused small decreases in pulmonary arterial pressure, larger decreases in systemic arterial pressure, and no change or small increases in cardiac output. Under elevated tone conditions during infusion of U-46619, intravenous injections of BAY 60-2770 caused larger decreases in pulmonary arterial pressure, smaller decreases in systemic arterial pressure, and increases in cardiac output. Pulmonary vasodilator responses to BAY 60-2770 were enhanced by L-NAME or by ODQ in a dose that attenuated responses to the NO donor sodium nitroprusside. ODQ had no significant effect on baseline pressures and attenuated pulmonary and systemic vasodilator responses to the sGC stimulator BAY 41-8543 2-{1-[2-(fluorophenyl)methyl]-1H-pyrazolo[3,4-b]pyridin-3-yl}-5(4-morpholinyl)-4,6-pyrimidinediamine. BAY 60-2770 and sodium nitroprusside decreased pulmonary and systemic arterial pressures in monocrotaline-treated rats in a nonselective manner. The present data show that BAY 60-2770 has vasodilator activity in the pulmonary and systemic vascular beds that is enhanced by ODQ and NOS inhibition, suggesting that the heme-oxidized form of sGC can be activated in vivo in an NO-independent manner to promote vasodilation. These results show that BAY 60-2770 and sodium nitroprusside decreased pulmonary and systemic arterial pressures in monocrotaline-treated rats, suggesting that BAY 60-2770 does not have selective pulmonary vasodilator activity in animals with monocrotaline-induced pulmonary hypertension.

Since its discovery, nitric oxide (NO) has been observed to play an important role in the physiology of single-celled organisms as well as high-order vertebrates. In this review, we will discuss the involvement of NO in bacterial, plant and human systems. NO originates from a variety of sources, namely bacterial, plant, and mammalian nitric oxide synthases which oxidize L-arginine. Bacterial NO is involved in toxin synthesis, signaling and biofilm formation. Organisms use NO to mediate oxidative stress incurred during the innate immune response. In plants, large amounts of NO hinder plant growth, while lower concentrations regulate normal development. NO and the associated reactive oxygen species (ROS) are effective antibacterial, anti-parasitic, and antifungal agents. Though NO has therapeutic effects in the immune system, the NO response is biphasic and concentration-dependent. NO promotes tumorigenesis within a concentration range, and induces apoptosis of cancerous cells at other concentrations. The biphasic response to NO is also evident in the regulation of chemokine, interleukins, and NF-κB, which can promote or inhibit inflammation. The physiologic response to NO is concentration dependent. NO, by way of non-adrenergic noncholinergic (NANC) nerve transmission, propagates a cascade of molecular signaling that facilitates smooth muscle cell relaxation and increased arterial inflow into the corpora, initiating an erectile response. Additional NO is released through NOS activity in the endothelium in response to cholinergic nerve activity and shear stress, which helps to maintain erection.

Objective: Salsalate is a dimeric form of salicylic acid that has been shown to have anti-inflammatory activity and to reduce glucose levels, insulin resistance, and cytokine expression. However, the effect of salsalate on vascular injury has not been determined. The objective of this study is to investigate the effect of salsalate on vascular injury and repair in a rat model of carotid artery balloon catheter injury., Research Design and Methods: Salsalate treatment was started in female Zucker fatty rats (insulin resistant) 1 week before carotid artery balloon catheter injury and continued for 21 days, at which time the animals were killed and studied., Results: Treatment with salsalate significantly decreased the intima-to-media ratio and upregulated the expression of aortic endothelial nitric oxide synthase (eNOS), phosphorylated eNOS (p-eNOS) (ser 1177), and manganese superoxide dismutase (MnSOD) and reduced serum interleukin (IL)-6 with concomitant downregulation of nuclear factor (NF) κB subunit p65 and vascular endothelial growth factor (VEGF) expression in the balloon-injured carotid artery of female Zucker fatty rats., Conclusions: The present study shows that salsalate treatment decreases vascular damage caused by balloon catheter injury in female Zucker fatty rats. The beneficial effect of salsalate on vascular injury was associated with upregulation of eNOS, p-eNOS, and MnSOD, which reduce oxidative stress and have anti-inflammatory properties, as evidenced by reduction in serum IL-6 and the downregulation of VEGF and NFκB, which promote inflammation without changing glucose levels. These results suggest that salsalate may be useful in reducing vascular injury and restenosis following interventional revascularization procedures.

Recovery from ambulatory surgical procedures can be limited by postoperative pain. Inadequate analgesia may delay or prevent patient discharge and can result in readmission. More frequently, postoperative pain produces discomfort and interrupts sleep, contributing to postoperative fatigue. The development of effective analgesic regimens for the management of postoperative pain is a priority especially in patients with impaired cardiorespiratory, hepatic, or renal function. Tramadol and tapentadol hydrochloride are novel in that their analgesic actions occur at multiple sites. Both agents are reported to be mu-opioid receptor agonists and monoamine-reuptake inhibitors. In contrast to pure opioid agonists, both drugs are believed to have lower risks of respiratory depression, tolerance, and dependence. The Food and Drug Administration has approved both drugs for the treatment of moderate-to-severe acute pain in adults. This article provides an evidence-based account of the role of tramadol and tapentadol in modern clinical practice., (Copyright © 2010 Elsevier Inc. All rights reserved.)

Nitric oxide (NO) plays an important role in states of erythrocyte dysfunction, including sickle cell disease (SCD), malaria, and banked blood preservation. By understanding the role of nitric oxide in these conditions, which are accompanied by hemolysis, vasoocclusion, and erythrocyte dysfunction, new therapeutic targets may be identified to treat complications of these disease states. Furthermore, the role of the erythrocyte in the controlled release of NO in hypoxic tissues is of particular interest, and two theories are discussed regarding this mechanism. In this article, the role of nitric oxide in erythrocyte function, sickle cell anemia, malaria, and damage to banked blood is reviewed, and the use of NO targeted therapies for erythrocyte disease states is discussed.

Pulmonary arterial hypertension (PAH) is a devastating disease with limited therapeutic options. Moreover, when PAH occurs in patients diagnosed with systemic sclerosis, worse outcomes are observed. The purpose of this review is to discuss the etiologies of PAH found in the systemic sclerosis patient, limitations of current medical therapies, and, finally, potential therapies for patients with this combination.

BAY 41-8543 is a nitric oxide (NO)-independent stimulator of soluble guanylyl cyclase (sGC). Responses to intravenous injections of BAY 41-8543 were investigated under baseline and elevated tone conditions and when NO synthase (NOS) was inhibited with N(ω)-nitro-L-arginine methyl ester (L-NAME). Under baseline conditions, intravenous injections of BAY 41-8543 caused small decreases in pulmonary arterial pressure, larger decreases in systemic arterial pressure, and increases in cardiac output. When pulmonary arterial pressure was increased to ∼30 mmHg with an intravenous infusion of U-46619, intravenous injections of BAY 41-8543 produced larger dose-dependent decreases in pulmonary arterial pressure, and the relative decreases in pulmonary and systemic arterial pressure in response to the sGC stimulator were similar. Treatment with L-NAME markedly decreased responses to BAY 41-8543 when pulmonary arterial pressure was increased to similar values (∼30 mmHg) in U-46619-infused and in U-46619-infused plus L-NAME-treated animals. The intravenous injection of a small dose of sodium nitroprusside (SNP) when combined with BAY 41-8543 enhanced pulmonary and systemic vasodilator responses to the sGC stimulator in L-NAME-treated animals. The present results indicate that BAY 41-8543 has similar vasodilator activity in the systemic and pulmonary vascular beds when pulmonary vasoconstrictor tone is increased with U-46619. These results demonstrate that pulmonary and systemic vasodilator responses to BAY 41-8543 are significantly attenuated when NOS is inhibited by L-NAME and show that vasodilator responses to BAY 41-8543 are enhanced when combined with a small dose of SNP in L-NAME-treated animals. The present results are consistent with the concept that pulmonary and systemic vasodilator responses to the sGC stimulator are NO-independent; however, the vasodilator activity of the compound is greatly diminished when endogenous NO production is inhibited with L-NAME. These data show that BAY 41-8543 has similar vasodilator activity in the pulmonary and systemic vascular beds in the rat.

Introduction: Erectile dysfunction (ED) afflicts 50% of diabetic men, many of whom experience poor results with phosphodiesterase type 5 inhibitors. The protein tyrosine kinase (PTK) inhibitor imatinib (Gleevec, Novartis Pharmaceuticals, Basel, Switzerland) has therapeutic potential in diabetic men by maintaining β-cell function., Aim: To determine if imatinib has a beneficial effect on erectile and vascular function in diabetic rats., Methods: Male Sprague-Dawley rats were divided into six groups: (i) control; (ii) imatinib (50mg/kg, daily gavage)-treated control; (iii) diabetic; (iv) preventive imatinib (8 weeks); (v) reversal imatinib (4 weeks untreated diabetes and 4 weeks of treatment); and (vi) insulin (8 weeks)-treated diabetic rats., Main Outcome Measures: After 8 weeks, all groups underwent cavernosal nerve stimulation and measurements of intracavernosal pressure (ICP) and mean arterial pressure (MAP). Contractile and relaxation responses were evaluated using isolated strips of corpus cavernosum smooth muscle (CCSM) and aorta., Results: Diabetic rats exhibited a 32% decrease in weight and fivefold increase in blood glucose levels. Imatinib-treated diabetic rats gained weight and partially improved blood glucose levels. Diabetic rats displayed a decrease in ICP/MAP. While maximum electrical field stimulation- and acetylcholine (ACh)-induced relaxations in CCSM strips from the diabetics were reduced, preventive imatinib or insulin treatment normalized ICP/MAP ratios and improved relaxation responses. ACh responses in diabetic aortas were diminished by 50.1% and restored by imatinib. While contractile responses to phenylephrine in diabetic CCSM were not altered, there was a significant enhancement (59.4 %) in the aortic contractile response in diabetic rats, which was restored by imatinib and insulin treatment., Conclusions: In diabetic rats, prolonged therapy with imatinib improves diabetes-related ED and vascular function, which may involve normalization of high glucose levels and restoration of PTK activation. Future studies are needed to elaborate on the actions of imatinib on diabetic vascular complications., (© 2010 International Society for Sexual Medicine.)

It has been reported that mitochondrial aldehyde dehydrogenase (ALDH2) catalyzes the formation of glyceryl dinitrate and inorganic nitrite from glyceryl trinitrate (GTN), leading to an increase in cGMP and vasodilation in the coronary and systemic vascular beds. However, the role of nitric oxide (NO) formed from nitrite in mediating the response to GTN in the pulmonary vascular bed is uncertain. The purpose of the present study was to determine if nitrite plays a role in mediating vasodilator responses to GTN. In this study, intravenous injections of GTN and sodium nitrite decreased pulmonary and systemic arterial pressures and increased cardiac output. The decreases in pulmonary arterial pressure under baseline and elevated tone conditions and decreases in systemic arterial pressure in response to GTN and sodium nitrite were attenuated by cyanamide, an ALDH2 inhibitor, whereas responses to the NO donor, sodium nitroprusside (SNP), were not altered. The decreases in pulmonary and systemic arterial pressure in response to GTN and SNP were not altered by allopurinol, an inhibitor of xanthine oxidoreductase, whereas responses to sodium nitrite were attenuated. GTN was approximately 1,000-fold more potent than sodium nitrite in decreasing pulmonary and systemic arterial pressures. These results suggest that ALDH2 plays an important role in the bioactivation of GTN and nitrite in the pulmonary and systemic vascular beds and that the reduction of nitrite to vasoactive NO does not play an important role in mediating vasodilator responses to GTN in the intact chest rat.

Recent studies have suggested the potential use of vasoactive intestinal peptide (VIP) in the treatment of pulmonary arterial hypertension (PAH). An understanding of the mechanism of action of VIP is important for the development of new therapies for PAH. The biological effects of VIP are mediated by two type II guanine nucleotide binding protein (G-protein)-coupled receptors VIP/PACAP (pituitary adenylate cyclase activating peptide) receptor type1 (VPAC1) and VIP/PACAP receptor type 2 (VPAC2). In the present study, the distribution and role of these receptors were investigated and compared in cultured smooth muscle cells from rat aorta and pulmonary artery, as well as in fixed tissue sections of the aorta and pulmonary artery. Western blot analysis, RT-PCR and immunohistochemistry showed the expression of both VIP receptors in tissue sections of the aorta and pulmonary artery as well as in cultured smooth muscle cells from these vessels. The application of a specific antagonist of VPAC1 resulted in a small release from VIP induced inhibition of cell proliferation. In contrast (VIP 6-28; 300nM) which is an antagonist against both receptors resulted in a significant restoration of proliferation. The expression of cAMP was reduced in the presence of VIP 6-28 and slightly decreased by VPAC1 antagonist. These findings suggest a dual role for VPAC1 and VPAC2 receptors in mediating the antiproliferative effects of VIP with VPAC2 appearing to play a more dominant role., (Copyright 2010 Elsevier Inc. All rights reserved.)

It has been reported that sodium nitrite (NaNO2) can act as a storage form of nitric oxide (NO) that can have beneficial pharmacologic actions. The present study was undertaken to investigate the effects of NaNO2 on erectile function in the rat. The intracavernosal (i.c.) injection of NaNO2 produced dose-related increases in i.c. pressure and decreases in systemic arterial pressure. NaNO2 was 1000-fold less potent than sodium nitroprusside in increasing i.c. pressure. Increases in i.c. pressure in response to NaNO2 were attenuated by the nitric oxide synthase (NOS) inhibitor N-nitro-L-arginine methyl ester (L-NAME). The increases in i.c. pressure in response to NaNO2 were not altered by the xanthine oxidoreductase inhibitor allopurinol. The decreases in systemic arterial pressure in response to i.c. injections of NaNO2 were attenuated by allopurinol and were either unchanged or increased by L-NAME. These data suggest that NaNO2 is converted to vasoactive NO in the corpora cavernosum and systemic vascular bed of the rat by different mechanisms. The present data suggest that the conversion of NaNO2 to vasoactive NO is mediated by NOS in the corpora cavernosum and by xanthine oxidoreductase in the systemic vascular bed of the rat. These data show NaNO2 can serve as a NO donor that increases erectile activity in the rat.

Study Type: Aetiology (case control) Level of Evidence 3b OBJECTIVE To evaluate the effect of N(G)-nitro-L-arginine methyl ester (L-NAME)-induced hypertension (HT) on erectile function in the rat and determine if the phosphodiesterase (PDE)-5 inhibitor, sildenafil, can reverse the effects of nitric oxide (NO) deficiency, as HT is a risk factor for erectile dysfunction (ED) and the NO synthase (NOS) inhibitor L-NAME induces NO-deficient HT., Materials and Methods: Thirty-six adult Sprague-Dawley male rats were divided into three groups, i.e. a control, L-NAME-HT (40 mg/rat/day in the drinking water for 4 weeks), and sildenafil-treated L-NAME-HT (1.5 mg/rat/day sildenafil, by oral gavage concomitantly with L-NAME). The erectile response expressed as a ratio of intracavernosal pressure (ICP)/mean arterial pressure (MAP), evaluated after electrical stimulation of the right cavernous nerve. The isometric tension of corpus cavernosum smooth muscle (CCSM) was measured in organ-bath experiments. NOS expression was determined immunohistochemically for neuronal (n)NOS and by Western blot analysis for endothelial (e) and inducible (i) NOS protein. cGMP levels were evaluated by enzyme-linked immunosorbent assay., Results: The erectile response was diminished in the HT group. Nitrergic and endothelium-dependent relaxation was reduced, while the relaxation response to sodium nitroprusside and contractile response to phenylephrine were not altered in CCSM from L-NAME-treated rats. HT rats showed decreased expression of nNOS, whereas eNOS and iNOS protein expression was increased. Sildenafil partly restored endothelial and molecular changes in CCSM from HT rats, but did not reverse the decreased erectile response, even as cGMP levels returned to normal levels., Conclusions: Sildenafil treatment did not correct the ED in L-NAME-treated HT rats. Under sustained high blood pressure, up-regulation of PDE5 expression failed to reverse the depletion of neuronal NO and/or impaired nNOS activity. However, endothelium-dependent relaxation was restored. Drug targeting of neuronal dysfunction might delay the onset of ED in HT.

Responses to the Rho kinase inhibitor Y-27632 were investigated in the anesthetized rat. Under baseline conditions intravenous injections of Y-27632 decreased pulmonary and systemic arterial pressures and increased cardiac output. The decreases in pulmonary arterial pressures were enhanced when baseline tone was increased with U-46619, and under elevated tone conditions Y-27632 produced similar percent decreases in pulmonary and systemic arterial pressures. Injections of Y-27632 prevented and reversed the hypoxic pulmonary vasoconstrictor response. The increase in pulmonary arterial pressure in response to ventilation with a 10% O(2)-90% N(2) gas mixture was not well maintained during the period of hypoxic exposure. Treatment with the nitric oxide (NO) synthase (NOS) inhibitor nitro-l-arginine methyl ester (l-NAME) increased pulmonary arterial pressure and prevented the decline or fade in the hypoxic pulmonary vasoconstrictor response. The hypoxic pulmonary vasoconstrictor response was reversed by Y-27632 in control and in l-NAME-treated animals. The Rho kinase inhibitor attenuated increases in pulmonary arterial pressures in response to intravenous injections of serotonin, angiotensin II, and Bay K 8644. Y-27632, sodium nitrite, and BAY 41-8543, a guanylate cyclase stimulator, decreased pulmonary and systemic arterial pressures and vascular resistances in monocrotaline-treated rats. These data suggest that Rho kinase is involved in the regulation of baseline tone and in the mediation of pulmonary vasoconstrictor responses. The present data suggest that the hypoxic pulmonary vasoconstrictor response is modulated by the release of NO that mediates the nonsustained component of the response in the anesthetized rat. These data suggest that Rho kinase and NOS play important roles in the regulation of vasoconstrictor tone in physiological and pathophysiological states and that monocrotaline-induced pulmonary hypertension can be reversed by agents that inhibit Rho kinase, generate NO, or stimulate soluble guanylate cyclase.

The organic nitrite, amyl of nitrite, was initially used as a therapeutic agent in the treatment of angina pectoris, but was replaced over a decade later by the organic nitrate, nitroglycerin (NTG), due to the ease of administration and longer duration of action. The administration of organic nitrate esters, such as NTG, continues to be used in the treatment of angina pectoris and heart failure since the birth of modern pharmacology. Their clinical effectiveness is due to vasodilator activity in large veins and arteries through an as yet unidentified method of delivering nitric oxide (NO), or a NO-like compound. The major drawback is the development of tolerance with NTG, and the duration and route of administration with amyl of nitrite. Although the nitrites are no longer used in the treatment of hypertension or ischemic heart disease, the nitrite anion has recently been discovered to possess novel pharmacologic actions, such as modulating hypoxic vasodilation, and providing cytoprotection in ischemia-reperfusion injury. Although the actions of these 2 similar chemical classes (nitrites and organic nitrates) have often been considered to be alike, we still do not understand their mechanism of action. Finally, the nitrite anion, either from sodium nitrite or an intermediate NTG form, may act as a storage form for NO and provide support for investigating the use of these agents in the treatment of ischemic cardiovascular states. We review what is presently known about the use of nitrates and nitrites including the historical, current, and potential uses of these agents, and their mechanisms of action.

Diabetes is increasing in the world and causes severe cardiovascular complications. Diabetes-induced limb ischemia leads to foot amputation and therapeutic remedies are urgently needed. Here we report that local injection of mesenchymal stem cells (MSCs) prestimulated with epidermal growth factor (EGF) restored blood flow and vasculogenesis in the ischemic hind-limb of type II diabetic (db(-)/db(-)) mice. Bone marrow cells from db(-)/db(-) mice are altered as evidenced by increased oxidative stress and reduced Akt and adhesion molecules when compared with control (db(-)/db(+)). Femoral artery ligation-induced ischemia was performed in the hind-limb of db(-)/db(-) and db(-)/db(+) mice for 28 days. Enhanced green fluorescent protein (EGFP)-MSCs stimulated+/-exogenous EGF for 24 h were injected locally into the ischemic muscle. Blood flow measured with MoorLDI-Laser and microangiography assessed with X-ray showed 100% recovery in db(-)/db(+) compared to 50% recovery in db(-)/db(-) mice. Interestingly, db(-)/db(-) mice had 60 and 96% blood flow recovery and 61 and 98% of vasculogenesis when treated with MSCs alone or MSCs modified with EGF, respectively. Western blot analysis of hind-limb muscles revealed an increase in Akt and vascular endothelial growth factor receptor phosphorylation and hypoxia-inducible factor) expression in db(-)/db(-) mice injected with MSCs or MSCs+EGF compared to db(-)/db(-) mice. Fluorescent microscopic images show that EGFP-MSCs differentiate into new microvessels. Adhesion and migration of MSCs on cultured endothelial cells were ICAM1-, VCAM1- and Akt-dependent mechanism and elevated when MSCs were prestimulated with EGF compared with nonstimulated MSCs. Our novel study data provide evidence that in type II diabetes, stimulated MSCs with EGF enhance the recovery of blood flow and angiogenesis.

Nitric oxide (NO)-sensitive soluble guanylyl cyclase (sGC) is the receptor that catalyzes the formation of the intracellular messenger cyclic guanosine monophosphate (cGMP). Binding of the physiological activator, NO, to the reduced heme moiety of sGC increases the conversion of guanosine triphosphate (GTP) to cyclic GMP (cGMP) and engages crucial effector systems such as protein kinases, phosphodiesterases, and ion channels. The development of compounds that activate sGC independent of NO release has therapeutic implications. Recent studies have demonstrated the potential use of heme-dependent sGC stimulators (e.g. YC-1, BAY 41-2272, BAY 41-8543, BAY 63-2521, CFM-1571 and A-350619) and heme-independent sGC activators (e.g. BAY 58-2667, HMR-1766, S-3448, A-778935) in the treatment of cardiovascular diseases. Erectile dysfunction (ED) affects millions of men. Phosphodiesterase (PDE)-5 inhibitors, produce an NO-dependent increase in intracellular cGMP concentration, have been a successful approach in the treatment of ED. However, >30% of men with ED do not respond to PDE-5 inhibitor therapy, implying that endogenous NO production may be impaired to such an extent that inhibition of cGMP degradation produces no significant therapeutic advantage. Endogenous NO released from nitrergic nerves in the corpora cavernosa is significantly decreased in various conditions (e.g. diabetes, aging, and hypertension) and have reduced activation of the NO-sGC-cGMP pathway. It is conceivable that sGC stimulators and/or activators may be more effective than PDE5 inhibitors in the treatment of ED in such circumstances by improving NO-sGC-cGMP signaling and erectile function. This novel drug therapy approach for the treatment of ED shows promise.

We studied the effect of a synthetic GLP-1 receptor agonist, exenatide, a drug approved for the treatment of type 2 diabetes, on the recovery from vascular injury in Zucker (non-diabetic) fatty rats. Exenatide 5.0 microg/kg per day or saline was administered for seven days before, and 21 days after balloon catheter mediated carotid injury. A pair feeding experiment helped differentiate between the drug itself and the known effects of the drug on decreased food intake. Body weight and glucose (weekly), carotid artery I/M ratio, aortic protein eNOS and NFkappaB-p65 were measured. Body weight gain in exenatide rats was significantly lower (53+/-5 vs. 89+/-8 g) than controls. Blood glucose did not change significantly. The I/M ratio in the exenatide group was 0.2+/-0.1 vs. 0.9+/-0.1 in controls (p<0.05). The expression of aortic eNOS was unchanged in exenatide treated rats and a small decrease seen in NFkappaB-p65 expression was not statistically significant. We conclude that exenatide attenuates intimal hyperplasia following balloon catheter induced vascular injury independently of glucose regulation and food intake. Our findings provide additional support for cardiovascular benefits of exenatide, especially in obese and pre-diabetic patients. Further research is needed to elucidate the mechanism underlying these effects.

Nitrite was a therapeutic agent used in the treatment of angina pectoris and hypertension, but was replaced by nitroglycerin. However, nitrite has recently been rediscovered following observations that this anion possesses novel pharmacologic actions such as producing vasodilation, modulating hypoxic vasodilation, and providing cytoprotection in ischemia-reperfusion injury. Moreover, recent observations in animal and human studies have demonstrated that the reduction of nitrite to vasoactive nitric oxide occurs through both enzymatic and non-enzymatic processes. These findings suggest that nitrite may act as a storage form for nitric oxide and provide support for investigating the use of nitrite in the treatment of ischemic disease states including pulmonary hypertension.

Pulmonary hypertension (PH) is a severe, life-threatening disease for which there are no effective curative therapies. A diverse group of agents such as prostacyclins, endothelin antagonists, phosphodiesterase inhibitors, calcium channel blockers, diuretics, inotropic agents, and anticoagulants are used to treat PH; however, none of these agents have a marked effect upon survival. Among the new agents that promise treatment of PH are rho-kinase inhibitors and soluble guanylate cyclase stimulators. Although these new classes of agents have beneficial effects in experimental animal models and clinical studies, they are not selective in their actions on the pulmonary vascular bed. This manuscript reviews the actions of rho-kinase inhibitors and soluble guanylate cyclase stimulators on the pulmonary vascular bed. It is our hypothesis that these new agents may be more effective than current therapies in the treatment of PH. Moreover, new methods in the delivery of these agents to the lung need to be developed so that their main effects will be exerted in the pulmonary vascular bed and their systemic effects can be minimized or avoided.

The development of right heart catheterization has provided the clinician the ability to diagnose patients with congenital and acquired right heart disease, and to monitor patients in the intensive care unit with significant cardiovascular illnesses. The development of bedside pulmonary artery catheterization has become a standard of care for the critically ill patient since its introduction into the intensive care unit almost 40 years ago. However, adoption of this procedure into the mainstream of clinical practice occurred without prior evaluation or demonstration of its clinical or cost-effectiveness. Moreover, current randomized, controlled trials provide little evidence in support of the clinical utility of pulmonary artery catheterization in the management of critically ill patients. Nevertheless, the right heart catheter is an important diagnostic tool to assist the clinician in the diagnosis of congenital heart disease and acquired right heart disease, and moreover, when catheter placement is proximal to the right auricle (atria), this catheter provides an important and safe route for administration of fluids, medications, and parenteral nutrition. The purpose of this manuscript is to review the development of right heart catheterization that led to the ability to conduct physiologic studies in cardiovascular dynamics in normal individuals and in patients with cardiovascular diseases, and to review current controversies of the extension of the right heart catheter, the pulmonary artery catheter.

Calcium is the major intracellular messenger that triggers smooth muscle contraction. The study of calcium-binding proteins, such as calmodulin and its downstream effectors, reveals critical regulation of smooth muscle contraction by protein kinases and phosphatases. Moreover, the small GTP-binding protein RhoA and its downstream effector protein, Rho-kinase, have been shown to play a novel role in the regulation of smooth muscle contraction. Studies have shown that the activation of Rho-kinase is involved in the development of endothelial dysfunction, inflammation, restenosis, and increased vascular tone in a number of cardiovascular disorders. Because inhibitors of this pathway promote vasodilation independent of the mechanism that increases vasoconstrictor tone, it is our hypothesis that Rho-kinase is constitutively active in regulating vasoconstrictor tone in the pulmonary and systemic vascular beds. Studies in the literature suggest that the RhoA/Rho-kinase pathway has an important role in the pathogenesis of pulmonary hypertension.

Erectile dysfunction (ED) is defined as the inability to attain and/or maintain penile erection sufficient for satisfactory sexual performance. Oxidative stress has been demonstrated to be involved in the pathophysiology of age- or diabetes-related ED. Superoxide dismutase (SOD), an antioxidant enzyme catalyzing the conversion of superoxide anion (O(2) (-)) to hydrogen peroxide (H(2)O(2)) and molecular oxygen (O(2)), is a promising therapeutic target for ED. In vivo gene therapy and adult stem cell-based ex vivo gene therapy are two attractive current gene therapies for the treatment of ED. In this chapter we describe the use of two potent gene transfer techniques to deliver the therapeutic gene extracellular superoxide dismutase (ecSOD) into the penis of aged or diabetic rats for therapy of ED: adenoviral-mediated intracavernosal ecSOD gene transfer for gene therapy of ED and ecSOD gene-modified marrow stromal cells, also known as mesenchymal stem cells, based stem cell and gene therapy.

Pulmonary hypertension (PH) is a serious, often fatal disease characterized by remodeling of the pulmonary vascular bed, increased pulmonary arterial pressure, and right heart failure. The increased vascular resistance in the pulmonary circulation is due to structural changes and increased vasoconstrictor tone. Although current therapies have prolonged survival, the long-term outcome is not favorable. Nitric oxide (NO) is synthesized by endothelial nitric oxide synthase (eNOS) and is important in regulating vascular resistance and in vascular remodeling in the lung. NO deficiency due to endothelial dysfunction plays an important role in the pathogenesis of PH. Therefore, local eNOS gene delivery to the lung is a promising approach for the treatment of PH. Adenoviral-mediated in vivo gene therapy and adult stem cell-based ex vivo gene therapy are two attractive current gene therapies for the treatment of cardiovascular and pulmonary diseases. In this chapter we describe the use of two gene transfer techniques, i.e., adenoviral gene transfer of eNOS and eNOS gene-modified rat marrow stromal cells, for eNOS gene delivery to the lung of laboratory animals for the treatment of PH.

Quantitative measurement of cellular oxidative stress (COS) and cytotoxicity are important to establish their significance in pathophysiologic conditions and disease states. So far, ample methods have been described to determine these processes based on spectrophotometric analysis. The application of simple, rapid, and sensitive fluorescence methods to determine the cytotoxicity and COS is described in the present chapter. Murine H9c2 cells were exposed to various free radical and non-free radical oxidants through use of diethylamine NONOate, 3-morpholinosydnonimine (SIN-1), and a synthetic preparation of peroxynitrite (PN). The viability of control and the treated H9c2 cells was measured based on the reduction of resazurin to resorufin which generates a fluorescent signal. The mitochondrial membrane potential was quantified by determining the cellular uptake of a fluorescent dye, (5,5('),6,6(')-tetrachloro-1,1(')-3,3(')-tetraethylbenzimidazolcarbocyanine iodide (JC-1)) and its segregation in the mitochondrial fraction. The intracellular GSH was determined by assaying the glutathione-S-transferase (GST)-catalyzed conjugation of GSH to monochlorobimane. This chapter describes the feasibility and potential of the above-described fluorescence approach as simple alternative methods to determine reactive oxygen and nitrogen species-induced cytotoxicity and oxidative stress using H9c2 cardiomyoblasts as a model system.

Erectile dysfunction (ED) affects up to 50% of men between the ages of 40 and 70. Treatment with PDE-5 inhibitors is effective in the majority of men with ED. However, PDE-5 inhibitors are not effective when levels of nitric oxide (NO), the principle mediator of erection, are low. The pharmacologic actions of three new potential treatments for ED are discussed in this paper: (1) sGC stimulators/activators, (2) Rho-kinase inhibitors, and (3) sodium nitrite.