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The higher incidence of cardiovascular disease in men than in women of similar age, and the menopause-associated increase in cardiovascular disease in women, has led to speculation that gender-related differences in sex hormones have a key role in the development and evolution of cardiovascular disease. Compelling data have indicated that sex differences in vascular biology are determined not only by gender-related differences in sex steroid levels, but also by gender-specific tissue and cellular differences that mediate sex-specific responses. In this Review, we describe the sex-specific effects of estrogen and testosterone on cardiovascular risk, direct vascular effects of these sex hormones, and how these effects influence development of atherosclerosis. Cardiovascular effects of exogenous hormone administration are also discussed. Importantly, evidence has indicated that estrogens alone or in combination with progestins in postmenopausal women increase cardiovascular risk if started late after menopause, but that it possibly has beneficial cardiovascular effects in younger postmenopausal women, although data on long-term testosterone therapy are lacking. Hormone therapy should not be considered solely for primary prevention or treatment of cardiovascular disease at this time. [ABSTRACT FROM AUTHOR]

Vascular smooth muscle contractile state is regulated by intracellular calcium levels. Nitric oxide causes vascular relaxation by stimulating production of cyclic GMP, which activates type I cGMP-dependent protein kinase (PKGI) in vascular smooth muscle cells (VSMC), inhibiting agonist-induced intracellular Ca2+ mobilization ([Ca2+]i). The relative roles of the two PKGI isozymes, PKGIα and PKGIβ, in cyclic GMP-mediated inhibition of [Ca2+]i in VSMCs are unclear. Here we have investigated the ability of PKGI isoforms to inhibit [Ca2+]i in response to VSMC activation. Stable Chinese hamster ovary cell lines expressing PKGIα or PKGIβ were created, and the ability of PKGI isoforms to inhibit [Ca2+]i in response to thrombin receptor stimulation was examined. In Chinese hamster ovary cells stably expressing PKGIα or PKGIβ, 8-Br-cGMP activation suppressed [Ca2+]i by thrombin receptor activation peptide (TRAP) by 98 ± 1 versus 42 ± 5%, respectively (p < 0.002). Immunoblotting studies of cultured human VSMC cells from multiple sites using PKGIα- and PKGIβ-specific antibodies showed PKGIα is the predominant VSMC PKGI isoform. [Ca2+]i following thrombin receptor stimulation was examined in the absence or presence of cyclic GMP in human coronary VSMC cells (Co403). 8-Br-cGMP significantly inhibited TRAP-induced [Ca2+]i in Co403, causing a 4-fold increase in the EC50 for [Ca2+]i. In the absence of 8-Br-cGMP, suppression of PKGIα levels by RNA interference (RNAi) led to a significantly greater TRAP-stimulated rise in [Ca2+]i as compared with control RNAi-treated Co403 cells. In the presence of 8-Br-cGMP, the suppression of PKGIα expression by RNAi led to the complete loss of cGMP-mediated inhibition of [Ca2+]i. Adenoviral overexpression of PKGIβ in Co403 cells was unable to alter TRAP-stimulated Ca2+ mobilization either before or after suppression of PKGIα expression by RNAi. These results support that PKGIα is the principal cGMP-dependent protein kinase isoform mediating inhibition of VSMC activation by the nitric oxide/cyclic GMP pathway. [ABSTRACT FROM AUTHOR]

Cardiovascular diseases (CVDs), the major cause of morbidity andmortality for both men and women, occur uncommonly in premenopausalwomen, but their incidence rises sharply after the menopausaltransition. Cardiovascular gender differences are apparent long beforeCVDs appear in men and women, and improved understanding of the biologyunderlying these differences has the potential to advance the diagnosisand treatment of CVDs in both sexes. This review considers genderdifferences in the molecular and cellular physiology of the heart andblood vessels in health and disease, highlighting understudied areasthat can help resolve the current controversy regarding hormonereplacement therapy and improve cardiovascular health in women. [ABSTRACT FROM AUTHOR]

Blood pressure abnormalities are thought to originate from intrinsic changes in the kidney, a concept that has been largely unchallenged for more than 4 decades. However, recent molecular, cellular, and transgenic mouse studies support an alternative hypothesis: primary abnormalities in vascular cell function can also directly cause abnormalities of blood pres- sure. In this issue of the JCI, Crowley and coworkers describe the application of an elegant cross-renal transplant model to type 1A angiotensin (AT1A) receptor-deficient mice and their wild-type littermates to explore the relative contributions of renal and extrarenal tissues to the low blood pressure seen in the AT1A receptor-deficient animals (see the related article beginning on page 1092). Their studies further support the emerging paradigm that primary abnormalities of the vasculature can make unique, nonredundant contributions to blood pressure regulation; the findings have potentially important implications for the ways we diagnose and treat blood pressure diseases in humans. [ABSTRACT FROM AUTHOR]

Nitric oxide (NO) and nitrovasodilators induce vascular smooth muscle cell relaxation in part by cGMP-dependent protein kinase (cGK)-mediated activation of myosin phosphatase, which dephosphorylates myosin light chains. We recently found that cGMP-dependent protein kinase 1α binds directly to the myosin-binding subunit (MBS) of myosin phosphatase via the leucine/isoleucine zipper of cGK. We have now studied the role of the leucine zipper domain of MBS in dimerization with cGK and the leucine/isoleucine zipper and leucine zipper domains of both proteins in homodimerization. Mutagenesis of the MBS leucine zipper domain disrupts cGKIα-MBS dimerization. Mutagenesis of the MBS leucine zipper eliminates MBS homodimerization, while similar disruption of the cGKIα leucine/isoleucine zipper does not prevent formation of cGK dimers. The MBS leucine zipper domain is phosphorylated by cGK, but this does not have any apparent effect on heterodimer formation between the two proteins. MBS LZ mutants that are unable to bind cGK were poor substrates for cGK. These data support the theory that the MBS leucine zipper domain is necessary and sufficient to mediate both MBS homodimerization and binding of the protein to cGK. In contrast, the leucine/isoleucine zipper of cGK is required for binding to MBS, but not for cGK homodimerization. These data support that the MBS and cGK leucine zipper domains mediate the interaction between these two proteins. The contribution of these domains to both homodimerization and their specific interaction with each other suggest that additional regulatory mechanisms involving these domains may exist. [Copyright &y& Elsevier]

Endothelial nitric-oxide synthase (eNOS), which generates the endogenous vasodilator, nitric oxide (NO), is highly regulated by post-translational modifications and protein interactions. We recently used purified proteins to characterize the mechanisms by which heat shock protein 90 (HSP90) increases eNOS activity at low and high Ca[sup 2+] levels (Takahashi, S. and Mendelsohn, M. E. (2003) J. Biol. Chem. 278, 9339-9344). Here we extend these studies to explore interactions between HSP90, Akt, and eNOS. In studies with purified proteins, HSP90 increased the initial rate and maximal extent of Akt-mediated eNOS phosphorylation and activation at low Ca[sup 2+] levels. Akt was not observed in the eNOS complex in the absence of HSP90, but both active and inactive Akt associated with eNOS in the presence of HSP90. Direct binding of Akt to HSP90 was observed even in the absence of eNOS. HSP90 also facilitated CaM binding to eNOS irrespective of Akt presence. Geldanamycin (GA) disrupted HSP90-eNOS binding, reduced HSP90-stimulated CaM binding, and blocked both recruitment of Akt to the eNOS complex and phosphorylation of eNOS at Ser-1179. Akt phosphorylated only CaM-bound eNOS, in an HSP90-independent manner. HSP90 and active Akt together increased eNOS activity synergistically, which was reversed by GA. In bovine aortic endothelial cells (BAECs), the effects of vascular endothelial growth factor (VEGF) and insulin on eNOS-HSP90-Akt complex formation and eNOS activation were compared. BAPTA-AM inhibited VEGF- but not insulin-induced eNOS-HSP90-Akt complex formation and eNOS phosphorylation. Insulin caused rapid, transient increase in eNOS activity correlated temporally with the formation of eNOS-HSP90-Akt complex. GA prevented insulin-induced association of HSP90, Akt and CaM with eNOS and inhibited eNOS activation in BAECs. Both platelet-derived growth factor (PDGF) and insulin induced activation of Akt in BAECs, but only insulin caused HSP90-Akt-eNOS association and eNOS phosphorylation. These results demonstrate that HSP90 and Akt synergistically activate eNOS and suggest that this synergy contributes to Ca[sup 2+]-independent eNOS activation in response to insulin. [ABSTRACT FROM AUTHOR]

Studies the calmodulin-dependent and calmodulin-independent activation of endothelial nitric-oxide synthase by heat shock protein 90. Generation of the endogenous vasodilator; Regulation of nitric acid by post-translational modifications and protein interactions; Stimulation of endothelial nitric oxide.

Estrogen receptors are best known as ligand-activated transcription factors that regulate vascular cell gene expression. For many years now, a rapid signaling pathway mediated by cell membrane-associated estrogen receptors also has been recognized, but the physiological relevance of this pathway has remained unclear. In this issue of the JCI, Chambliss et al. provide new data to indicate that activation of non-nuclear estrogen receptor signaling regulates processes central to cardiovascular health and disease. These investigators show that an estrogen-dendrimer conjugate (EDC), which activates estrogen receptors but remains non-nuclear, stimulates vascular EC migration in vitro and protects against vascular injury in vivo. They show further that the vascular benefits of EDC in vivo occur selectively in the vasculature, without stimulating the uterus or enhancing growth of breast cancer xenografts. Taken together, these findings indicate that activation of non-nuclear estrogen receptor signaling regulates vascular events of physiological relevance and suggest that translation of these findings into clinically relevant therapeutic interventions is a logical next goal. [ABSTRACT FROM AUTHOR]

The article reports on the relationship between hormone-replacement therapy (HRT) and heart disease. The article discusses the Women's Health Initiative (WHI), which is a large-scale trial funded by the National Institutes of Health (NIH) to determine the effects of HRT on (mostly menopausal) women. An additional study, the WHI Coronary-Artery Calcium Study (WHI-CACS), reported a dramatic reduction in coronary calcification in women who had undergone estrogen treatment. The study reported that HRT can help prevent atherosclerosis if it is administered before advanced atherosclerosis develops. The author discusses the relationship between HRT drugs as cardiovascular treatment and the biological characteristics of blood vessels.

Reports on the finding that sildenafil (Viagra) can suppress cardiac hypertrophy and improve heart function in mice exposed to chronic pressure overload. Reversal and normalization of pre-established cardiac enlargement due to pressure overload; Role of cyclic guanylic acid (cGMP) for both membrane-bound guanylate cyclase receptors and for the ubiquitous signaling molecule nitric oxide.

Estrogen has direct and indirect effects on the cardiovascular system that are mediated by the estrogen receptors ER-alpha and ER-beta. The direct effects of estrogen occur through rapid nongenomic and longer-term genomic pathways. The rapid effects of estrogen are mediated by ERs and result in the activation of endothelial nitric oxide synthase, leading to arterial vasodilation. Longer-term effects involve changes in gene and protein expression, modulating the response to injury and atherosclerosis. Estrogen also indirectly influences serum lipoprotein and triglyceride profiles, and the expression of coagulant and fibrinolytic proteins. Advanced atherosclerosis and certain progestins, however, may attenuate some of the protective effects of estrogen. [ABSTRACT FROM AUTHOR]

Reports on the benefits of estrogen particularly with regard to avoiding cardiovascular disease and atherosclerotic diseases. Proposed explanations for why estrogen is so beneficial; Molecular structure and function of estrogen; Its effects on serum lipid concentrations and other systems, which can contribute to cardiovascular disease; Effects of menopause; Health benefits to estrogen therapy in postmenopausal women.

Phosphodiesterase 5 inhibition (PDE5i) activates cGMP‐dependent protein kinase (PKG) and ameliorates heart failure; however, its impact on cardiac mitochondrial regulation has not been fully determined. Here, we investigated the role of the mitochondrial regulator peroxisome proliferator‐activated receptor γ co‐activator‐1α (PGC1α) in the PDE5i‐conferred cardioprotection, utilizing PGC1α null mice. In PGC1α+/+ hearts exposed to 7 weeks of pressure overload by transverse aortic constriction, chronic treatment with the PDE5 inhibitor sildenafil improved cardiac function and remodeling, with improved mitochondrial respiration and upregulation of PGC1α mRNA in the myocardium. By contrast, PDE5i‐elicited benefits were abrogated in PGC1α−/− hearts. In cultured cardiomyocytes, PKG overexpression induced PGC1α, while inhibition of the transcription factor CREB abrogated the PGC1α induction. Together, these results suggest that the PKG–PGC1α axis plays a pivotal role in the therapeutic efficacy of PDE5i in heart failure. [ABSTRACT FROM AUTHOR]

Regulation of vascular smooth muscle cell contractile state is critical for the maintenance of blood vessel tone. Abnormal vascular smooth muscle cell contractility plays an important role in the pathogenesis of hypertension, blood vessel spasm, and atherosclerosis. Myosin phosphatase, the key enzyme controlling myosin light chain dephosphorylation, regulates smooth muscle cell contraction. Vasoconstrictor and vasodilator pathways inhibit and activate myosin phosphatase, respectively. G-protein-coupled receptor agonists can inhibit myosin phosphatase and cause smooth muscle cell contraction by activating RhoA/Rho kinase, whereas NO/cGMP can activate myosin phosphatase and cause smooth muscle cell relaxation by activation of cGMP-dependent protein kinase. We have used yeast two-hybrid screening to identify a 116-kDa human protein that interacts with both myosin phosphatase and RhoA. This myosin phosphatase-RhoA interacting protein, or M-RIP, is highly homologous to murine p116[sup RIP3], is expressed in vascular smooth muscle, and is localized to actin myofilaments. M-RIP binds directly to the myosin binding subunit of myosin phosphatase in vivo in vascular smooth muscle cells by an interaction between coiled-coil and leucine zipper domains in the two proteins. An adjacent domain of M-RIP directly binds RhoA in a nucleotide-independent manner. M-RIP copurifies with RhoA and Rho kinase, colocalizes on actin stress fibers with RhoA and MBS, and is associated with Rho kinase activity in vascular smooth muscle cells. M-RIP can assemble a complex containing both RhoA and MBS, suggesting that M-RIP may play a role in myosin phosphatase regulation by RhoA. [ABSTRACT FROM AUTHOR]

Inhibition of cGMP-specific phosphodiesterase 5 (PDE5) ameliorates pathological cardiac remodeling and has been gaining attention as a potential therapy for heart failure. Despite promising results in males, the efficacy of the PDE5 inhibitor sildenafil in female cardiac pathologies has not been determined and might be affected by estrogen levels, given the hormone's involvement in cGMP synthesis. Here, we determined that the heart-protective effect of sildenafil in female mice depends on the presence of estrogen via a mechanism that involves myocyte Enos--dependent cGMP synthesis and the cGMP-dependent protein kinase Iα (PKGIα). Sildenafil treatment failed to exert antiremodeling properties in female pathological hearts from Gαq-overexpressing or pressure-overloaded mice after ovary removal; however, estrogen replacement restored the effectiveness of sildenafil in these animals. In females, sildenafil-elicited myocardial PKG activity required estrogen, which stimulated tonic cardiomyocyte cGMP synthesis via an eNOS/soluble guanylate cyclase pathway. In contrast, eNOS activation, cGMP synthesis, and sildenafil efficacy were not estrogen dependent in male hearts. Estrogen and sildenafil had no impact on pressure-overloaded hearts from animals expressing dysfunctional PKGIα, indicating that PKGIα mediates antiremodeling effects. These results support the importance of sex differences in the use of PDE5 inhibitors for treating heart disease and the critical role of estrogen status when these agents are used in females. [ABSTRACT FROM AUTHOR]

Hypertensive heart disease causes significant mortality in older patients, yet there is an incomplete understanding of molecular mechanisms that regulate age-dependent hypertensive left ventricular hypertrophy (LVH). Therefore, we tested the hypothesis that the cGMP-dependent protein kinase G I alpha (PKGIα) attenuates hypertensive LVH by evaluating the cardiac phenotype in mice with selective mutations of the PKGIα leucine zipper domain. These leucine zipper mutant (LZM) mice develop basal hypertension. Compared with wild-type controls, 8-month-old adult LZM mice developed increased left ventricular end-diastolic pressure but without frank LVH. In advanced age (15 months), the LZM mice developed overt pathological LVH. These findings reveal a role of PKGIα in normally attenuating hypertensive LVH. Therefore, mutation of the PKGIα LZ domain produces a clinically relevant model for hypertensive heart disease of aging. [ABSTRACT FROM PUBLISHER]

Background and objective: Nitric oxide (NO) and related nitrovasodilators regulate blood pressure by activation of soluble guanylate cyclase, elevation of cyclic guanosine monophosphate (cGMP), and activation of cGMP-dependent protein kinase (cGPK). Despite the progress of our understanding of the NO/cGMP mediated vasorelaxation, partly through conventional cGPK knock-out mice, the role of cGPK remains unclear. In particular, the downstream target(s) of the kinase are not well defined. We hypothesized that highly selective inhibitors of cGPK delivered in vivo in adult may elucidate the role of the kinase in vasorelaxation and regulation of blood pressure. Methods and results: We have adopted a newly developed method of TAT-mediated protein transduction to study NO/cGMP signaling pathways in mice. In vitro, TAT-cGPK inhibitor peptide blocked autophosphorylation of the kinase. The effect of cGPK inhibition on murine blood pressure (BP) was investigated by continuous infusion of 100μg of the inhibitor into the internal jugular vein over 72hours. In 8 animals infused with the inhibitor, the mean BP increased by 38±24/31±30mm Hg (from 108±14/92±19 to 145±13/123±19mm Hg) whereas in 8 animals injected with either saline (4) or TAT-green fluorescent protein (4), the BP remained the same (from 117±21/101±26 to 119±22/96±30mm Hg); P =0.001. Ex vivo, using vascular ring assays, NO-dependent relaxation in murine aortas harvested from animals administered with TAT-cGPK inhibitor was inhibited by 25% (sham 76±11%, inhibitor 51±13%). Conclusion: We demonstrated that highly specific peptide inhibitor of cGPK induced adult murine hypertension through inhibition of nitric oxide mediated relaxation. [ABSTRACT FROM AUTHOR]

NO, via its second messenger cGMP, activates protein kinase GI (PKGI) to induce vascular smooth muscle cell relaxation. The mechanisms by which PKGI kinase activity regulates cardiovascular function remain incompletely understood. Therefore, to identify novel protein kinase G substrates in vascular cells, a λ phage coronary artery smooth muscle cell library was constructed and screened for phosphorylation by PKGI. The screen identified steroid-sensitive gene 1 (SSG1),which harbors several predicted PKGI phosphorylation sites. We observed direct and cGMP-regulated interaction between PKGI and SSG1. In cultured vascular smooth muscle cells, both the NO donor S-nitrosocysteine and atrial natriuretic peptide induced SSG1 phosphorylation, and mutation of SSG1 at each of the two predicted PKGI phosphorylation sites completely abolished its basal phosphorylation by PKGI. We detected high SSG1 expression in cardiovascular tissues. Finally, we found that activation of PKGI with cGMP regulated SSG1 intracellular distribution. [ABSTRACT FROM AUTHOR]

Vascular smooth muscle cell (VSMC) tone is regulated by the state of myosin light chain (MLC) phosphorylation, which is in turn regulated by the balance between MLC kinase and MLC phosphatase (MLCP) activities. RhoA activates Rho kinase, which phosphorylates the regulatory subunit of MLC phosphatase, thereby inhibiting MLC phosphatase activity and increasing contraction and vascular tone. Nitric oxide is an important mediator of VSMC relaxation and vasodilation, which acts by increasing cyclic GMP (cGMP) levels in VSMC, thereby activating cGMP-dependent protein kinase Iα (PKGIα). PKGI is known to phosphorylate Rho kinase, preventing Rho-mediated inhibition of MLC phosphatase, promoting vasorelaxation, although the molecular mechanisms that mediate this are unclear. Here we identify RhoA as a target of activated PKGIα and show further that PKGIα binds directly to RhoA, inhibiting its activation and translocation. In protein pulldown and immunoprecipitation experiments, binding of RhoA and PKGIα was demonstrated via a direct interaction between the amino terminus of RhoA (residues 1-44), containing the switch I domain of RhoA, and the amino terminus of PKGIα (residues 1-59), which includes a leucine zipper heptad repeat motif. Affinity assays using cGMP-immobilized agarose showed that only activated PKGIα binds RhoA, and a leucine zipper mutant PKGIα was unable to bind RhoA even if activated. Furthermore, a catalytically inactive mutant of PKGIα bound RhoA but did not prevent RhoA activation and translocation. Collectively, these results support that RhoA is a PKGIα target and that direct binding of activated PKGIα to RhoA is central to cGMP-mediated inhibition of the VSMC Rho kinase contractile pathway. [ABSTRACT FROM AUTHOR]

Hypertension is a cardiovascular risk factor present in over two-thirds of people over age 60 in North America; elevated blood pressure correlates with increased risk of heart attack, stroke and progression to heart and kidney failure. Current therapies are insufficient to control blood pressure in almost half of these patients. The mineralocorticoid receptor (MR), acting in the kidney, is known to regulate blood pressure through aldosterone binding and stimulation of sodium retention. However, recent studies support the concept that the MR also has extrarenal actions and that defects in sodium handling alone do not fully explain the development of hypertension and associated cardiovascular mortality. We and others have identified functional MR in human vascular smooth muscle cells (SMCs), suggesting that vascular MR might directly regulate blood pressure. Here we show that mice with SMC-specific deficiency of the MR have decreased blood pressure as they age without defects in renal sodium handling or vascular structure. Aged mice lacking MR in SMCs (SMC-MR) have reduced vascular myogenic tone, agonist-dependent contraction and expression and activity of L-type calcium channels. Moreover, SMC-MR contributes to angiotensin II-induced vascular oxidative stress, vascular contraction and hypertension. This study identifies a new role for vascular MR in blood pressure control and in vascular aging and supports the emerging hypothesis that vascular tone contributes directly to systemic blood pressure. [ABSTRACT FROM AUTHOR]

Background--Heart failure is a major cause of morbidity and mortality worldwide. The ubiquitously expressed cytokine transforming growth factor-&bgr;l (TGF&bgr;1) promotes cardiac fibrosis, an important component of progressive heart failure. Membrane-associated endoglin is a coreceptor for TGF&bgr;1signaling and has been studied in vascular remodeling and preeclampsia. We hypothesized that reduced endoglin expression may limit cardiac fibrosis in heart failure. Methods and Results--We first report that endoglin expression is increased in the left ventricle of human subjects with heart failure and determined that endoglin is required for TGF&bgr;1 signaling in human cardiac fibroblasts using neutralizing antibodies and an siRNA approach. We further identified that reduced endoglin expression attenuates cardiac fibrosis, preserves left ventricular function, and improves survival in a mouse model of pressure-overloadinduced heart failure. Prior studies have shown that the extracellular domain of endoglin can be cleaved and released into the circulation as soluble endoglin, which disrupts TGF&bgr;1 signaling in endothelium. We now demonstrate that soluble endoglin limits TGF&bgr;1 signaling and type I collagen synthesis in cardiac fibroblasts and further show that soluble endoglin treatment attenuates cardiac fibrosis in an in vivo model of heart failure. Conclusion--Our results identify endoglin as a critical component of TGF&bgr;1 signaling in the cardiac fibroblast and show that targeting endoglin attenuates cardiac fibrosis, thereby providing a potentially novel therapeutic approach for individuals with heart failure. [ABSTRACT FROM AUTHOR]

Progressive left ventricular (LV) dysfunction induces expression of the cytokine transforming growth factor-β1. Endoglin (CD105) is a transforming growth factor-β1 co-receptor that is released into the circulation as soluble endoglin (sEng). The objective of the present study was to assess the serum levels of sEng in patients with heart failure and to identify the predictive value of sEng for detecting elevated left ventricular end-diastolic pressures (LVEDPs). We measured the sEng levels in 82 consecutive patients with suspected LV dysfunction referred for determination of left heart filling pressures using cardiac catheterization. Among these subjects, the sEng levels correlated with the LVEDP (R = 0.689; p <0.0001), irrespective of the LV ejection fraction. Using a receiving operating characteristic curve, the sEng levels predicted an LVEDP of ≥16 mm Hg with an area under the curve of 0.85, exceeding the measured area under the curves for both atrial and brain natriuretic peptide, currently used biomarkers for heart failure diagnosis (atrial natriuretic peptide 0.68 and brain natriuretic peptide 0.65; p <0.01 vs sEng). In 10 subjects receiving medical therapy guided by invasive hemodynamic monitoring for heart failure, decreased a pulmonary capillary wedge pressure was associated with a reduced sEng level (R = 0.75, p = 0.008). Finally, compared to 25 healthy controls, the sEng levels were elevated in subjects with suspected LV dysfunction (3,589 ± 588 vs 4,257 ± 966 pg/ml, respectively, p <0.005) and correlated directly with the New York Heart Association class (R = 0.501, p<0.001). In conclusion, circulating levels of sEng are elevated in patients with increased LVEDP and New York Heart Association class, irrespective of the LV ejection fraction. sEng levels also decreased in association with a reduced cardiac filling pressure after diuresis. These findings have identified circulating sEng as a sensitive measure of elevated left heart filling pressures. [Copyright &y& Elsevier]

In clinical trials, aldosterone antagonists reduce cardiovascular ischemia and mortality by unknown mechanisms. Aldosterone is a steroid hormone that signals through renal mineralocorticoid receptors (MRs) to regulate blood pressure. MRs are expressed and regulate gene transcription in human vascular cells, suggesting that aldosterone might have direct vascular effects. Using gene expression profiling, we identify the pro-proliferative VEGF family member placental growth factor (PGF) as an aldosterone-regulated vascular MR target gene in mice and humans. Aldosterone-activated vascular MR stimulated Pgf gene transcription and increased PGF protein expression and secretion in the mouse vasculature. In mouse vessels with endothelial damage and human vessels from patients with atherosclerosis, aldosterone enhanced expression of PGF and its receptor, FMS-like tyrosine kinase 1 (Flt1). In atherosclerotic human vessels, MR antagonists inhibited PGF expression. In vivo, aldosterone infusion augmented vascular remodeling in mouse carotids following wire injury, an effect that was lost in Pgf-/- mice. In summary, we have identified PGF as what we believe to be a novel downstream target of vascular MR that mediates aldosterone augmentation of vascular injury. These findings suggest a non-renal mechanism for the vascular protective effects of aldosterone antagonists in humans and support targeting the vascular aldosterone/MR/PGF/Flt1 pathway as a therapeutic strategy for ischemic cardiovascular disease. [ABSTRACT FROM AUTHOR]

Background: Sequencing of the human genome has identified numerous chromosome copy number additions and subtractions that include stable partial gene duplications and pseudogenes that when not properly annotated can interfere with genetic analysis. As an example of this problem, an evolutionary chromosome event in the primate ancestral chromosome 18 produced a partial duplication and inversion of rho-associated protein kinase 1 (ROCK1 - 18q11.1, 33 exons) in the subtelomeric region of the p arm of chromosome 18 detectable only in humans. ROCK1 and the partial gene copy, which the gene databases also currently call ROCK1, include non-unique single nucleotide polymorphisms (SNPs). Results: Here, we characterize this partial gene copy of the human ROCK1, termed Little ROCK, located at 18p11.32. Little ROCK includes five exons, four of which share 99% identity with the terminal four exons of ROCK1 and one of which is unique to Little ROCK. In human while ROCK1 is expressed in many organs, Little ROCK expression is restricted to vascular smooth muscle cell (VSMC) lines and organs rich in smooth muscle. The single nucleotide polymorphism database (dbSNP) lists multiple variants contained in the region shared by ROCK1 and Little ROCK. Using gene and cDNA sequence analysis we clarified the origins of two non-synonymous SNPs annotated in the genome to actually be fixed differences between the ROCK1 and the Little ROCK gene sequences. Two additional coding SNPs were valid polymorphisms selectively within Little ROCK. Little ROCK-Green Fluorescent fusion proteins were highly unstable and degraded by the ubiquitin-proteasome system in vitro. Conclusion: In this report we have characterized Little ROCK (ROCK1P1), a human expressed pseudogene derived from partial duplication of ROCK1. The large number of pseudogenes in the human genome creates significant genetic diversity. Our findings emphasize the importance of taking into consideration pseudogenes in all candidate gene and genome-wide association studies, as well as the need for complete annotation of human pseudogenome. [ABSTRACT FROM AUTHOR]

Bicuspid Aortic Valve (BAV) is a highly heritable congenital heart defect. The low frequency of BAV (1% of general population) limits our ability to perform genome-wide association studies. We present the application of four a priori SNP selection techniques, reducing the multiple-testing penalty by restricting analysis to SNPs relevant to BAV in a genome-wide SNP dataset from a cohort of 68 BAV probands and 830 control subjects. Two knowledge-based approaches, CANDID and STRING, were used to systematically identify BAV genes, and their SNPs, from the published literature, microarray expression studies and a genome scan. We additionally tested Functionally Interpolating SNPs (fitSNPs) present on the array; the fourth consisted of SNPs selected by Random Forests, a machine learning approach. These approaches reduced the multiple testing penalty by lowering the fraction of the genome probed to 0.19% of the total, while increasing the likelihood of studying SNPs within relevant BAV genes and pathways. Three loci were identified by CANDID, STRING, and fitSNPS. A haplotype within the AXIN1-PDIA2 locus (p-value of 2.926×10-06) and a haplotype within the Endoglin gene (p-value of 5.881×10-04) were found to be strongly associated with BAV. The Random Forests approach identified a SNP on chromosome 3 in association with BAV (p-value 5.061×10-06). The results presented here support an important role for genetic variants in BAV and provide support for additional studies in well-powered cohorts. Further, these studies demonstrate that leveraging existing expression and genomic data in the context of GWAS studies can identify biologically relevant genes and pathways associated with a congenital heart defect. [ABSTRACT FROM AUTHOR]

Background: Endothelium-derived nitric oxide plays an important role for the bone marrow microenvironment. Since several important effects of nitric oxide are mediated by cGMP-dependent pathways, we investigated the role of the cGMP downstream effector cGMP-dependent protein kinase I (cGKI) on postnatal neovascularization. Methodology/Principal Findings: In a disc neovascularization model, cGKI-/- mice showed an impaired neovascularization as compared to their wild-type (WT) littermates. Infusion of WT, but not cGKI-/- bone marrow progenitors rescued the impaired ingrowth of new vessels in cGKI-deficient mice. Bone marrow progenitors from cGKI-/- mice showed reduced proliferation and survival rates. In addition, we used cGKIa leucine zipper mutant (LZM) mice as model for cGKI deficiency. LZM mice harbor a mutation in the cGKIa leucine zipper that prevents interaction with downstream signaling molecules. Consistently, LZM mice exhibited reduced numbers of vasculogenic progenitors and impaired neovascularization following hindlimb ischemia compared to WT mice. Conclusions/Significance: Our findings demonstrate that the cGMP-cGKI pathway is critical for postnatal neovascularization and establish a new role for cGKI in vasculogenesis, which is mediated by bone marrow-derived progenitors. [ABSTRACT FROM AUTHOR]

The heart initially compensates for hypertension-mediated pressure overload by enhancing its contractile force and developing hypertrophy without dilation. Gq protein-coupled receptor pathways become activated and can depress function, leading to cardiac failure. Initial adaptation mechanisms to reduce cardiac damage during such stimulation remain largely unknown. Here we have shown that this initial adaptation requires regulator of G protein signaling 2 (RGS2). Mice lacking RGS2 had a normal basal cardiac phenotype, yet responded rapidly to pressure overload, with increased myocardial Gq signaling, marked cardiac hypertrophy and failure, and early mortality. Swimming exercise, which is not accompanied by Gq activation, induced a normal cardiac response, while Rgs2 deletion in Galphaq-overexpressing hearts exacerbated hypertrophy and dilation. In vascular smooth muscle, RGS2 is activated by cGMP-dependent protein kinase (PKG), suppressing Gq-stimulated vascular contraction. In normal mice, but not Rgs2-/- mice, PKG activation by the chronic inhibition of cGMP-selective phosphodiesterase 5 (PDE5) suppressed maladaptive cardiac hypertrophy, inhibiting Gq-coupled stimuli. Importantly, PKG was similarly activated by PDE5 inhibition in myocardium from both genotypes, but PKG plasma membrane translocation was more transient in Rgs2-/- myocytes than in controls and was unaffected by PDE5 inhibition. Thus, RGS2 is required for early myocardial compensation to pressure overload and mediates the initial antihypertrophic and cardioprotective effects of PDE5 inhibitors. [ABSTRACT FROM AUTHOR]

Nitric oxide and nitrovasodilators induce vascular smooth muscle cell relaxation in part by cGMP-dependent protein kinase I (PKG-Iα)-mediated activation of myosin phosphatase (MLCP). Mechanistically it has been proposed that protein-protein interactions between the N-terminal leucine zipper (LZ) domain of PKG-Iα ((PKG-I1-59) and the LZ and/or coiled coil (CC) domain of the myosin binding subunit (MBS) of MLCP are localized in the C terminus of MBS. Although recent studies have supported these interactions, the critical amino acids responsible for these interactions have not been identified. Here we present structural and biophysical data identifying that the LZ domain of PKG-Iα1-59 interacts with a well defined 42-residue CC motif (MBSCT42) within the C terminus of MBS. Using glutathione S-transferase pulldown experiments, chemical cross-linking, size exclusion chromatography, circular dichroism, and isothermal titration calorimetry we identified a weak dimer-dimer interaction between PKG-Iα1-59 and this C-terminal CC domain of MBS. The Kd of this non-covalent complex is 178.0 ± 1.5 μM. Furthermore our 1H-15N heteronuclear single quantum correlation NMR data illustrate that this interaction is mediated by several PKG-Iα residues that are on the a, d, e, and g hydrophobic and electrostatic interface of the C-terminal heptad layers 2, 4, and 5 of PKG-I. Taken together these data support a role for the LZ domain of PKG-Iα and the CC domain of MBS in this requisite contractile complex. [ABSTRACT FROM AUTHOR]

Hypertension, a major cardiovascular risk factor and cause of mortality worldwide, is thought to arise from primary renal abnormalities. However, the etiology of most cases of hypertension remains unexplained. Vascular tone, an important determinant of blood pressure, is regulated by nitric oxide, which causes vascular relaxation by increasing intracellular cGMP and activating cGMP-dependent protein kinase I (PKGI). Here we show that mice with a selective mutation in the N-terminal protein interaction domain of PKGIα display inherited vascular smooth muscle cell abnormalities of contraction, abnormal relaxation of large and resistance blood vessels, and increased systemic blood pressure. Renal function studies and responses to changes in dietary sodium in the PKGIα mutant mice are normal. These data reveal that PKGIα is required for normal VSMC physiology and support the idea that high blood pressure can arise from a primary abnormality of vascular smooth muscle cell contractile regulation, suggesting a new approach to the diagnosis and therapy of hypertension and cardiovascular diseases. [ABSTRACT FROM AUTHOR]

Abstract: Plasma lipid profile is affected by endogenous estrogen levels and hormone replacement therapy (HRT). As plasma lipid concentrations have a significant heritable basis and the effects of both endogenous estrogen and use of HRT are mediated by estrogen receptors, we sought to investigate the relationships between polymorphisms in estrogen receptor-α (ESR1) and plasma lipid and lipoprotein concentrations. We analyzed data from 854 women (mean age 52±10 years) from the Framingham Heart Study. A TA repeat in the promoter region, c.30T > C in exon 1, c.454-397T > C, and c.454-351A > G in intron 1, all in linkage disequilibrium (LD), were significantly associated with low-density lipoprotein (LDL) particle size and concentration of small LDL particles. Women with the c.454-397C allele had larger LDL particle size (21.09±0.02nm versus 21.01±0.03nm, p =0.021) concurrent with lower small LDL particle concentration (0.47±0.02mmol/L versus 0.58±0.03mmol/L, p =0.008). Moreover, the TA[L]–c.30C–c.454-397C–c.454-351G haplotype (frequency, 32%) was associated with lower small LDL particle concentrations (−0.06±0.03mmol/L change associated with each copy of this haplotype, p =0.011) when compared to the TA[S]–c.30T–c.454-397T–c.454-351A haplotype (frequency, 46%), where L and S are long and short TA repeats. Our results suggest that common ESR1 polymorphisms have a significant effect on lipoprotein metabolism in women. [Copyright &y& Elsevier]

Left ventricular (LV) remodeling after myocardial infarction (MI) results from hypertrophy of myocytes and activation of fibroblasts induced, in part, by ligand stimulation of the ANG II type 1 receptor (AT1R). The purpose of the present study was to explore the specific role for activation of the AT1aR subtype in post-MI remodeling and whether gentler differences exist in the patterns of remodeling in wild-type and AT1aR knockout (KO) mice. AT1aR-KO mice and wild-type littermates underwent coronary ligation to induce MI or sham procedures; echocardiography and hemodynamic evaluation were performed 6 wk later, and LV tissue was harvested for infarct size determination, morphometric measurements, and gene expression analysis. Survival and infarct size were similar among all male and female wild-type and AT1aR-KO mice. Hemodynamic indexes were also similar except for lower systolic blood pressure in the AT1aR-KO mice compared with wild-type mice. Male and female wild-type and male AT1aR-KO mice developed similar increases in LV chamber size, LV mass corrected for body weight (LV/BW), and myocyte cross-sectional area (CSA). However, female AT1aR-KO mice demonstrated no increase in LV/BW and myocyte CSA post-MI compared with shams. Both male and female wild-type mice demonstrated higher atrial natriuretic peptide (ANP) levels after MI, with female wild types being significantly greater than males. However, male and female AT1aR-KO mice developed no increase in ANP gene expression with MI despite an increase in LV mass and myocyte size in males. These data support that gender-specific patterns of LV and myocyte hypertrophy exist after MI in mice with a disrupted AT1aR gene, and suggest that myocyte hypertrophy post-MI in females relies, in part, on activation of the AT1aR. Further work is necessary to explore the potential mechanisms underlying these gender-based differences. [ABSTRACT FROM AUTHOR]

Steroid hormone receptors (SHRs) are ligand-activated transcription factors that regulate gene expression. SHRs also mediate rapid, nongenomic cellular activation by steroids. In vascular endothelial cells, the SHR for estrogen, estrogen receptor (ER) α, is targeted by unknown mechanisms to a functional signaling module in membrane caveolae that enables estrogen to rapidly activate the mitogen-activated protein kinase and phosphatidylinositol 3-Akt kinase pathways, and endothelial NO synthase (eNOS). Here we identify the 110-kDa caveolin-binding protein striatin as the molecular anchor that localizes ERα to the membrane and organizes the ERα-eNOS membrane signaling complex. Striatin directly binds to amino acids 183-253 of ERα, targets ERα to the cell membrane, and serves as a scaffold for the formation of an ERα-Gαi complex. Disruption of complex formation between ERα and striatin blocks estrogen-induced rapid activation mitogen-activated protein kinase, Akt kinase, and eNOS, but has no effect on ER-dependent regulation of an estrogen response element-driven reporter plasmid. These findings identify striatin as a molecular scaffold required for rapid, nongenomic estrogen-mediated activation of downstream signaling pathways. Furthermore, by demonstrating independent regulation of nongenomic vs. genomic FR-dependent signaling, these findings provide conceptual support for the potential development of "pathway-specific" selective ER modulators. [ABSTRACT FROM AUTHOR]

Excitation-contraction coupling in smooth muscle involves activation of myosin light chain (MLC) phosphorylation, which increases activity of the myosin actin-activated ATPase, resulting in contraction. Phosphorylation of MLC phosphatase (SMPP-1M) by Rho-associated kinase or endogenous SMPP-1M-associated kinase inhibits SMPP-1M, enhancing MLC phosphorylation and contraction. However, the precise identity of SMPP-1M-associated kinase remains unclear. Biochemical evidence strongly supports the idea that SMPP-1M-associated kinase is related to the human serine/threonine leucine zipper-interacting protein kinase (hZIPK), which is important in cell apoptosis, and the SMPP-1M-associated kinase has therefore been called ZIP-like kinase (MacDonald, J. A., Borman, M. A., Murani, A., Somlyo, A. V., Hartshorne, D. J., and Haystead, T. A. J. (2001) Proc. Natl. Acad. Sci. U. S. A. 98, 2419–2424). Whether the vascular smooth muscle SMPP-1M-associated kinase is a truncated version of hZIPK, native hZIPK, or a unique homologue of hZIPK is unclear. Here we show that only native hZIPK mRNA and protein are detectable in human vascular smooth muscle cells (VSMCs). High stringency screening of a human aortic cDNA library for the SMPP-1M-associated kinase identified 18 positive clones, all of which proved to be clones of hZIPK. PCR-based studies of VSMC RNA revealed native hZIPK transcripts but no evidence for splice variants of hZIPK or a ZIP-like kinase. Northern blotting studies of multiple vascular and non-vascular tissue RNAs, including human bladder RNA, showed only 2.3 kb of mRNA predicted for full-length hZIPK. Immunoblotting showed native full-length 52-kDa hZIPK expression in VSMCs. Full-length and N-terminal hZIPK bound the C-terminal domain (amino acids 681– 847) of the myosin binding subunit (MBS) of SMPP-1M. hZIPK immunoprecipitated with the MBS of SMPP-1M and dominant negative RhoA inhibited the hZIPK-MBS interaction. These data identify hZIPK as the unique SMPP-1-associated kinase expressed in human vesicular smooth muscle and support a role for Rho in promoting the hZIPK-MBS interaction. [ABSTRACT FROM AUTHOR]

Cyclic GMP-dependent protein kinase I (PKGI) mediates vascular relaxation by nitric oxide and related nitrovasodilators and inhibits vascular smooth muscle cell (VSMC) migration. To identify VSMC proteins that interact with PKGI, the N-terminal protein interaction domain of PKGIα was used to screen a yeast two-hybrid human aortic cDNA library. The formin homology (FH) domain-containing protein, FHOD1, was found to interact with PKGIα in this screen. FH domain-containing proteins bind Rho-family GTPases and regulate actin cytoskeletal dynamics, cell migration, and gene expression. Antisera to FHOD1 were raised and used to characterize FHOD1 expression and distribution in vascular cells. FHOD1 is highly expressed in human coronary artery, aortic smooth muscle cells, and in human arterial and venous endothelial cells. In glutathione S-transferase pull-down experiments, the FHOD1 C terminus (amino acids 964–1165) binds full-length PKGI. Both in vitro and intact cell studies demonstrate that the interaction between FHOD1 and PKGI is decreased 3- to 5-fold in the presence of the PKG activator, 8Br-cGMP. Immunofluorescence studies of human VSMC show that FHOD1 is cytoplasmic and is concentrated in the perinuclear region. PKGI also directly phosphorylates FHOD1, and studies with wild-type and mutant FHOD1-derived peptides identify Ser-1131 in the FHOD1 C terminus as the unique PKGI phosphorylation site in FHOD1. These studies demonstrate that FHOD1 is a PKGI-interacting protein and substrate in VSMCs and show that cyclic GMP negatively regulates the FHOD1-PKGI interaction. Based on the known functions of FHOD1, the data are consistent with a role for FHOD1 in cyclic GMP-dependent inhibition of VSMC stress fiber formation and/or migration. [ABSTRACT FROM AUTHOR]

Context: Estrogen and related hormone therapies activate estrogen receptors, which in turn regulate genes for several cardiovascular disease (CVD) risk factors. Relatively little is known, however, about the impact of genetic variation in estrogen receptor alpha (ESR1) on CVD risk.Objective: To investigate whether the ESR1 c.454-397T>C polymorphism is associated with CVD risk.Design, Setting, and Participants: Prospective study of 1739 unrelated men and women from the population-based offspring cohort of the Framingham Heart Study, who were followed up from 1971 to 1998.Main Outcome Measures: Total atherosclerotic CVD events, defined as recognized or unrecognized myocardial infarction (MI), angina pectoris, coronary insufficiency, intermittent claudication, coronary heart disease death, or atherothrombotic stroke (n = 178); major atherosclerotic CVD, defined as recognized acute MI, coronary insufficiency, coronary heart disease death, or atherothrombotic stroke (n = 83); and recognized acute MI (n = 59).Results: Twenty percent of participants (n = 352) were homozygous for the ESR1 c.454-397C allele. After adjustment for covariates (age, sex, body mass index, hypertension, diabetes mellitus, total cholesterol, high-density lipoprotein cholesterol, and cigarette smoking), the CC genotype was significantly associated with major atherosclerotic CVD, with an odds ratio of 2.0 (95% confidence interval [CI], 1.3-3.2; P =.004) compared with individuals with the CT or TT genotypes. Participants with the CC genotype had 3.0-fold greater odds of MI (95% CI, 1.7-5.2; P<.001) compared with those with the CT or TT genotype. The results remained significant when analyses were restricted to men; too few women had events to study them separately.Conclusions: Individuals with the common ESR1 c.454-397CC genotype have a substantial increase in risk of MI. Whether ESR1 c.454-397T>C is causally related to MI risk or in linkage disequilibrium with 1 or more causal variants remains to be determined. These findings support the importance of estrogen receptors in CVD susceptibility, especially in men. Estrogen receptor variation also has potential to explain recent conflicting data regarding the effects of hormone therapy on CVD susceptibility in women. [ABSTRACT FROM AUTHOR]

Context: Estrogen and related hormone therapies activate estrogen receptors, which in turn regulate genes for several cardiovascular disease (CVD) risk factors. Relatively little is known, however, about the impact of genetic variation in estrogen receptor α (ESR1) on CVD risk. Objective: To investigate whether the ESR1 c.454-397T>C polymorphism is associated with CVD risk. Design, Setting, and Participants: Prospective study of 1739 unrelated men and women from the population-based offspring cohort of the Framingham Heart Study, who were followed up from 1971 to 1998. Main Outcome Measures: Total atherosclerotic CVD events, defined as recognized or unrecognized myocardial infarction (MI), angina pectoris, coronary insufficiency, intermittent claudication, coronary heart disease death, or atherothrombotic stroke (n = 178); major atherosclerotic CVD, defined as recognized acute MI, coronary insufficiency, coronary heart disease death, or atherothrombotic stroke (n = 83); and recognized acute MI (n = 59). Results: Twenty percent of participants (n = 352) were homozygous for the ESR1 c.454-397C allele. After adjustment for covariates (age, sex, body mass index, hypertension, diabetes mellitus, total cholesterol, high-density lipoprotein cholesterol, and cigarette smoking), the CC genotype was significantly associated with major atherosclerotic CVD, with an odds ratio of 2.0 (95% confidence interval [CI], 1.3-3.2; P = .004) compared with individuals with the CT or TT genotypes. Participants with the CC genotype had 3.0-fold greater odds of MI (95% CI, 1.7-5.2; P<.001) compared with those with the CT or TT genotype. The results remained significant when analyses were restricted to men; too few women had events to study them separately. Conclusions: Individuals with the common ESR1 c.454-397CC genotype have a substantial increase in risk of MI. Whether ESR1 c.454-397T>C is causally related to MI risk or in linkage disequilibrium with 1 or more causal var... [ABSTRACT FROM AUTHOR]

: ObjectivesThis study was designed to examine the effects of estrogen replacement on infarct size, ventricular remodeling, and mortality after myocardial infarction (MI) in mice.: BackgroundObservational and clinical studies suggest that the cardiovascular effects of hormone replacement therapy can differ depending on the patient population studied. No prospective studies have examined the effect of estrogen on outcomes following MI. We now examine the effects of estrogen replacement on infarct size, ventricular remodeling, and mortality after MI in mice.: MethodsMyocardial infarction was induced by left coronary artery ligation in ovariectomized female mice treated with 17-beta-estradiol (E2) or placebo. At either one day or six weeks after MI, hemodynamic function was assessed, animals were euthanized, and infarct size was determined.: Results17-Beta-estradiol–treated mice had smaller infarcts than placebo-treated animals both one day (18% decrease; p < 0.01), and six weeks (14% decrease; p < 0.05) following MI. E2 reduced cardiomyocyte apoptosis as assessed by the terminal deoxynucleotidyl transferase uridine nucleotide end-labeling method (50% reduction, p < 0.05) and caspase 3 activation (33% reduction, p < 0.05). Despite having smaller infarcts, however, left ventricular mass increased more in the E2-treated animals (16% greater; p < 0.01). Left ventricular weight was positively correlated with infarct size in the estrogen-treated animals (R2 = 0.79, p = 0.0001). 17-Beta-estradiol treatment also significantly increased mortality in the infarcted animals (relative risk of death = 2.4; 95% confidence interval 1.2 to 5.3).: ConclusionsEstrogen replacement therapy reduces infarct size and cardiomyocyte apoptosis in mice. However, estrogen increased post-MI ventricular remodeling and mortality. Further studies will be necessary to elucidate the mechanisms underlying the complex effects of estrogen observed in the present study. [Copyright &y& Elsevier]

Blood vessels express estrogen receptors, but their role in cardiovascular physiology is not well understood. We show that vascular smooth muscle cells and Blood vessels from estrogen receptor β (ERβ)-deficient mice exhibit multiple functional abnormalities. In wild-type mouse blood vessels, estrogen attenuates vasoconstriction by an ERβ-mediated increase in inducible nitric oxide synthase expression. In contrast, estrogen augments vasoconstriction in blood vessels from ERβ-deficient mice. Vascular smooth muscle cells isolated from ERβ-deficient mice show multiple abnormalities of ion channel function. Furthermore, ERβ-deficient mice develop sustained systolic and diastolic hypertension as they age. These data support an essential role for ERβ in the regulation of vascular function and blood pressure. [ABSTRACT FROM AUTHOR]

Atherosclerosis is the primary cause of cardiovascular disease, and the risk for atherosclerosis is inversely proportional to circulating levels of high-density lipoprotein (HDL) cholesterol. However, the mechanisms by which HDL is atheroprotective are complex and not well understood. Here we show that HDL stimulates endothelial nitric oxide synthase (eNOS) in cultured endothelial cells. In contrast, eNOS is not activated by purified forms of the major HDL apolipoproteins ApoA-I and ApoA-II or by low-density lipoprotein. Heterologous expression experiments in Chinese hamster ovary cells reveal that scavenger receptor-BI (SR-BI) mediates the effects of HDL on the enzyme. HDL activation of eNOS is demonstrable in isolated endothelial-cell caveolae where SR-BI and eNOS are colocalized, and the response in isolated plasma membranes is blocked by antibodies to ApoA-I and SR-BI, but not by antibody to ApoA-II. HDL also enhances endothelium- and nitric-oxide?dependent relaxation in aortae from wild-type mice, but not in aortae from homozygous null SR-BI knockout mice. Thus, HDL activates eNOS via SR-BI through a process that requires ApoA-I binding. The resulting increase in nitric-oxide production might be critical to the atheroprotective properties of HDL and ApoA-I. [ABSTRACT FROM AUTHOR]

Provides information on a study demonstrating that cGMP prevents TXA2 receptors from coupling to, and activating their cognate G proteins, in addition to showing that the TXA2 receptors themselves are substrates for G kinase in vivo. Methodology used to conduct the study; Results of the study.

Presents information on a study on ventricular remodeling following myocardial infarction in a mouse. Importance of transgenic strains of mice as experimental species; Methods used in the study; Results of the study.

Presents information on a study which examined the point to which left ventricular remodeling occurs after myocardial infarction in wild-type mice, while assessing the workability of quantifying hemodynamics and parameters of ventricular remodeling. Why mice are important in the study of cardiovascular disease; Illustration of a thoracotomy in which epicardial ischemia was induced.

Introduction: Myocardial cyclic GMP (cGMP) elevation and activation of cGMP-dependent protein kinase (PKG) have been shown to attenuate pathological cardiac hypertrophy and remodeling. Expression of cardiac phosphodiesterase 9A (PDE9) is increased in HF patients and in mouse models of cardiac hypertrophy. PDE9 catalyses the breakdown of cGMP and has been shown to promote cardiac hypertrophy. Recent evidence suggests that PDE9 inhibition may be beneficial in HF, increasing cGMP and exerting anti-hypertrophic effects via PKG stimulation. A novel PDE9 inhibitor, CRD-733, has demonstrated safety in both preclinical and human studies, but has not yet been studied in models of hypertrophy. Hypothesis: PDE9 inhibition with CRD-733 can reverse established pressure overload-induced LVH in a murine model of HF. Methods: Left ventricular hypertrophy (LVH) was induced by transaortic constriction (TAC) in male C57/BL6J mice (n=58), alongside sham controls (n=10). On day 7, after established LVH, TAC mice were randomized to vehicle (n=17); or to CRD-733 at doses of 200 (n=10), 600 (n=10), 1000 (n=10) or 2000 (n=11) mg/kg/day by oral gavage (days 7-21). Primary endpoints included organ weights, echocardiography and invasive hemodynamics. Results: TAC induced a 53% increase in LV weight normalized to tibia length in vehicle treated mice at day 21 (7.71±0.29mg/mm vs. sham 5.04±0.15mg/mm; P<0.001). This increase was attenuated in mice treated with 600, 1000, and 2000 mg/kg/day CRD-733 (maximum reduction of 2.0±0.11 mg/mm, to 5.71±0.26 mg/mm, 75% reduction from vehicle; P<0.001). These findings were associated with complete normalization of TAC-induced increases in lung mass (P<0.001) and trends towards lower LV end diastolic pressure in drug-treated TAC mice (13.0±1.4mmHg in CRD-733 600mg/kg/day vs. 21.0±3.1mmHg in vehicle; P=0.08). Echocardiographic analysis showed that TAC-induced cardiac hypertrophy and left atrial dilation were reversed from day 6 to day 20 with CRD-733 treatment, but not with vehicle (P<0.05). Conclusion: CRD-733 reversed TAC-induced cardiac hypertrophy in mice and led to a reduction in lung mass, left atrial size, and LV end diastolic pressure. These findings support the potential of CRD-733 as a novel therapeutic agent in HF. [ABSTRACT FROM AUTHOR]

Presents a correction to the article "Regulator of G-Protein Signaling-2 Mediates Vascular Smooth Muscle Relaxation and Blood Pressure" that was previously published in the 2003 issue of "Nature Medicine," Volume 9.