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This study investigated the effects of irisin on vascular smooth muscle contractility in rat thoracic aorta, and the hypothesis that mitogen-activated protein kinase kinase (MEK1/2) signaling pathway, voltage-gated potassium ([K.sub.V]) channels, small-conductance calcium-activated potassium ([SK.sub.Ca]) channels, and large-conductance calcium-activated potassium ([BK.sub.Ca]) channels may have roles in these effects. Isometric contraction-relaxation responses of isolated thoracic aorta rings were measured with an organ bath model. The steady contraction was induced with [10.sup.-5] M phenylephrine (PHE), and then the concentration-dependent responses of irisin ([10.sup.-9] - [10.sup.-6] M) were examined in endothelium-intact and - denuded rat thoracic aortas. Also, the effects of irisin incubations on PHE-mediated contraction and acetylcholine (ACh)--mediated relaxation were studied. Irisin exerted the vasorelaxant effects in both endothelium-intact and -denuded aortic rings at concentrations of [10.sup.-8], [10.sup.-7], and [10.sup.-6] M compared with the control groups (p < 0.001). Besides, pre-incubation of aortic rings with irisin (10 nM, 100 nM, or 1 [micro]M for 30 min) augmented ACh-mediated ([10.sup.9] - [10.sup.5]) vasodilation in PHE-precontracted thoracic aorta segments but did not modulate PHE-mediated ([10.sup.9] - [10.sup.5]) contraction. In addition, MEK1/2 inhibitor U0126, [K.sub.V] channel blocker XE-991, [SK.sub.Ca] channel blocker apamin, and [BK.sub.Ca] channel blocker tetraethylammonium (TEA) incubations significantly inhibited the irisin-induced relaxation responses. In conclusion, the first physiological findings were obtained regarding the functional relaxing effects of irisin in rat thoracic aorta. The findings demonstrated that irisin induces relaxation responses in endothelium-intact and (or) endothelium-denuded aortic rings in a concentration-dependent manner. Furthermore, this study is the first to report that irisin-induced relaxation responses are related to the activity of the MEK1/2 pathway, [K.sub.V] channels, and calcium-activated [K.sup.+] ([SK.sub.Ca] and [BK.sub.Ca]) channels. Key words: irisin, rat thoracic aorta, vasodilation, mitogen-activated protein kinase kinase, potassium channels. Cette etude portait sur les effets de l'irisine sur la contractilite du muscle lisse vasculaire dans l'aorte thoracique de rat, avec pour hypothese que la voie de signalisation de la MEK1/2 (pour << mitogen-activated protein kinase kinase >>), les canaux potassiques dependants du voltage ([K.sub.V]), les canaux potassiques a faible conductance actives par le calcium ([SK.sub.Ca]) et les canaux potassiques a conductance elevee actives par le calcium ([BK.sub.Ca]) peuvent jouer un role dans ces effets. Nous avons mesure la contraction et la relaxation isometriques dans des anneaux isoles d'aorte thoracique en bain d'organe. Nous avons obtenu la contraction stable a l'aide de phenylephrine (PHE) a [10.sup.-5] M, puis examine les reactions dependantes des concentrations d'irisine ([10.sup.-9] - [10.sup.-6] M) dans des aortes thoraciques de rats denudees et dont l'endothelium etait intact. Nous avons aussi etudie les effets de l'incubation en presence d'irisine sur la contraction mediee par la PHE et la relaxation mediee par l'acetylcholine (ACh). Dans les anneaux dont l'endothelium etait intact comme denudes, l'irisine entrainait des effets vasorelaxants plus marques que chez les temoins a des concentrations de [10.sup.-8], de [10.sup.-7] et de [10.sup.-6] M (p < 0,001). Par ailleurs, l'incubation prealable des anneaux aortiques en presence d'irisine (10 nM, 100 nM ou 1 [micro]M pendant 30 minutes) entrainait une augmentation de la vasodilatation mediee par l'ACh ([10.sup.9] - [10.sup.5]) dans les segments d'aorte thoracique precontractes a l'aide de PHE, mais sans modulation de la contraction mediee par la PHE ([10.sup.9] - [10.sup.5]). De plus, l'incubation en presence de U0126 (un inhibiteur de la MEK1/2), de XE-991 (un bloqueur des canaux [K.sub.V]), d'apamine (un bloqueur des canaux [SK.sub.Ca]) et de tetraethylammonium (ou TEA, un bloqueur des canaux [BK.sub.Ca]) entrainait une inhibition marquee de la relaxation entrainee par l'irisine. En conclusion, nous avons obtenu les premiers resultats physiologiques quant a la relaxation fonctionnelle entrainee par l'irisine dans l'aorte thoracique chez le rat. Les resultats ont montre avec des anneaux aortiques denudes et/ou dont l'endothelium etait intact que l'irisine entraine des relaxations proportionnelles a la concentration. En outre, il s'agit de la premiere etude qui rapporte que les relaxations entrainees par l'irisine sont liees a l'activite de la voie de signalisation de la MEK1/2, des canaux [K.sub.V] et des canaux [K.sub.+] actives par le calcium ([SK.sub.Ca] et [BK.sub.Ca]). [Traduit par la Redaction] Mots-cles : irisine, aorte thoracique de rat, vasodilatation, MEK1/2, canaux potassiques., 1. Introduction Irisin, a newly identified hormone containing 112 amino acids that is secreted mainly by skeletal muscle cells during exercise, is a cleavage product of fibronectin type III domain-containing [...]

Many studies have demonstrated that chronic intermittent hypobaric hypoxia (CIHH) can reduce blood pressure in spontaneously hypertensive rats and renovascular hypertensive (RVH) rats in which endothelial dysfunction is determined as a critical factor. However, whether CIHH can regulate vasodilation of the aorta in RVH rats remains unknown. The purpose of this study was to investigate the effect of CIHH on impaired relaxation of the aorta in the 2-kidney, 1-clip (2K1C) RVH rat model. The results showed CIHH improved the impaired endothelium-dependent relaxation in the 2K1C rat aorta. The endothelial dysfunction was prevented by the p38 antagonist SB203580, but not by the ERK1/2 antagonist PD98059 or JNK antagonist SP600125. Furthermore, the expression of p-eNOS, HIF-1[alpha], and HIF-2[alpha] increased while that of p-p38 and BMP-4 decreased in CIHH-treated aortas from 2K1C rats. Finally, the p-eNOS expression was upregulated and the p-p38 expression was downregulated by preincubation of SB203580 or the BMP-4 antagonist Noggin with the aorta. CIHH ameliorated the impairment of endothelium dependent relaxation through upregulating the expression of p-eNOS, which may be mediated by the inhibition of BMP-4/p-p38 MAPK, and upregulating the expression of HIFs in the 2K1C rat aorta. Key words: 2K1C rats, chronic intermittent hypobaric hypoxia, endothelium-dependent relaxation, p38, BMP-4. De nombreuses etudes ont montre que l'hypoxie hypobarique intermittente chronique (HHIC) peut entrainer une diminution de la tension arterielle chez les rats spontanement hypertendus et les rats presentant une hypertension renovasculaire (HRV), modele avec lequel on a etabli que le dysfonctionnement endothelial constitue un facteur determinant. Toutefois, on ne sait toujours pas si l'HHIC peut reguler la vasodilatation de l'aorte chez les rats HRV. Ces travaux avaient pour but d'etudier l'effet de l'HHIC sur l'atteinte de la relaxation de l'aorte dans le modele d'HRV 2 reins 1 clip (2R1C) chez le rat. Les resultats ont montre que l'HHIC permet d'attenuer l'atteinte de la relaxation de l'aorte dependante de l'endothelium dans l'aorte de rat 2R1C. Le dysfonctionnement endothelial a ete empeche par le SB203580 (un antagoniste de p38), mais pas par le PD98059 (un antagoniste d'ERK1/2), ni par le SP600125 (un antagoniste de JNK). En outre, l'expression de p-eNOS, d'HIF-1[alpha] et d'HIF-2[alpha] augmentait alors que celle de p-p38 et de BMP-4 diminuait dans les aortes de rats 2R1C exposes a l'HHIC. Enfin, l'expression de p-eNOS etait regulee a la hausse et celle de p-p38 etait regulee a la baisse en cas de pre-incubation de l'aorte avec le SB203580 ou le noggin (un antagoniste de BMP-4). L'HHIC permettait d'attenuer l'atteinte de la relaxation dependante de l'endothelium par l'intermediaire de la regulation a la hausse de l'expression de p-eNOS--laquelle pourrait etre mediee par l'inhibition de la voie de signalisation BMP-4/p-p38 MAPK--et la regulation a la hausse de l'expression des HIF dans l'aorte de rats 2R1C. [Traduit par la Redaction] Mots-cles: rats 2 reins 1 clip, hypoxie hypobarique intermittente chronique, relaxation dependante de l'endothelium, p38, BMP-4., Introduction Hypertension is caused by pathological changes in renal and vascular structures (Curb et al. 1996). Accumulated studies have shown that endothelial dysfunction could contribute to elevated blood pressure in [...]

Hyperglycemia affects male and female vascular beds differently. We have previously shown that 1 week after the induction of diabetes with streptozotocin (STZ), male and female rats exhibit differences in aortic endothelial function. To examine this phenomenon further, aortic responses were studied in male and female rats 8 weeks after the induction of diabetes (intermediate stage). Endothelium-dependent vasodilation (EDV) to acetylcholine (ACh) was measured in phenylephrine (PE) pre-contracted rat aortic rings. Concentration response curves to PE were generated before and after L-NAME, a nitric oxide synthase (NOS) inhibitor. Furthermore, mRNA expression of endothelial nitric oxide synthase (eNOS) and NADPH oxidase subunit (Nox1) were determined. At 8 weeks, diabetes impaired EDV to a greater extent in female than male aortae. Furthermore, the responsiveness to PE was significantly enhanced only in female diabetic rats, and basal NO, as indicated by the potentiation of the response to PE after L-NAME, was reduced in female diabetic rat aortae to the same levels as in males. In addition, eNOS Mrna expression was decreased, while the Nox1 expression was significantly enhanced in diabetic female rats. These results suggest that aortic function in female diabetic rats after 8 weeks exhibits a more prominent impairment and that NO may be involved. Key words: sex differences, endothelial function, nitric oxide, streptozotocin (STZ), diabetes, rat aorta. On sait que l'hyperglycemie n'affecte pas le lit vasculaire de la meme maniere chez les hommes que chez les femmes. De fait, nous avons montre precedemment qu'une semaine apres l'induction du diabete par l'administration de streptozotocine (STZ), la fonction endotheliale de l'aorte de rats males est differente de celle des rats femelles. En vue d'examiner ce phenomene plus en detail, nous avons etudie les reponses aortiques chez des rats males et femelles 8 semaines apres l'induction du diabete (stade intermediaire). A cet effet, nous avons mesure la vasodilation dependante de l'endothelium (VDE) induite par l'acetylcholine (ACh) dans un modele d'anneaux aortiques contractes en reponse a la phenylephrine (PE). Les courbes de la reponse a la PE en fonction de la concentration etaient obtenues avant et apres l'administration de L-NAME, un inhibiteur de l'oxyde nitrique synthase (NOS). Par la suite, nous avons mesure l'expression de l'ARNm de l'oxyde nitrique synthase endotheliale (NOSe) et de la sous-unite NADPH oxydase (Nox1). Huit semaines apres l'induction du diabete, nous avons observe que la VDE etait plus marquee chez les femelles que chez les males et que la susceptibilite aux effets de la PE n'augmentait de facon importante que chez les rates diabetiques. En revanche, comme en temoignait la potentialisation de la reponse a la PE induite par l'administration de L-NAME, l'effet initial du NO etait attenue a des degres similaires dans les aortes de rats diabetiques males et femelles. Enfin, nous avons observe une diminution de l'expression de l'ARNm de la NOSe et une augmentation marquee de l'expression de la Nox1 chez les rats diabetiques femelles. Ces resultats laissent entendre qu'apres 8 semaines, le diabete aurait un effet plus deletere sur le fonctionnement de l'aorte chez les rats femelles, et que ce phenomene serait lie au NO. [Traduit par la Redaction] Mots-cles: differences entre les sexes, fonction endotheliale, oxyde nitrique, streptozotocine (STZ), diabete, aorte de rat., Introduction Cardiovascular diseases (CVD) are main causes of morbidity and mortality in diabetes. Both micro- and macro-vascular complications play a major role in the development of CVD in diabetic patients. [...]

ABSTRACT Schizophyllum commune (SC) is widely consumed by Chinese, especially in southern part of China. The aim of the present study was to assess the extract of SC on vascular [...]

Oxidatively modified low-density lipoprotein (LDL) has been implicated in the development of cardiovascular disease, the leading cause of morbidity and mortality worldwide. While the exact mechanism by which oxidized LDL contributes to CVD has not been fully elucidated, it is believed that inhibiting LDL oxidation may provide protection against CVD. Previous studies have indicated that antioxidants such as green tea (GT) and thymoquinone (TQ) may reduce the damage caused by oxidized LDL. Therefore, the specific aim of this study is to determine the effects of GT and TQ on the modification of LDL using endothelial cells as a model. Male and female human aortic endothelial cells (HAEC) were challenged with LDL, alone or in combination, with TQ and GT, and the functional capacity of the cells was evaluated. Results of the study suggest that TQ and GT may be effective in preventing the damage caused by LDL oxidation. Keywords: cardiovascular disease, green tea, thymoquinone, endothelial cells, LDL, antioxidants, INTRODUCTION A report by the American Heart Association estimates that approximately 83.6 million American adults have one or more types of CVD [1]. Although mortality rates from CVD have declined [...]

Hydrogen sulfide ([H.sub.2]S), an endogenous gaseous mediator, produces both vasorelaxation and vasoconstriction at different concentrations. We found in the present study that NaHS, an [H.sub.2]S donor, produced stronger vasorelaxant and weaker vasoconstrictive effects in HEPES solution compared with those achieved in Krebs solution. We further screened the buffer components and found that bicarbonate (HC[O.sup.-.sub.3]) was the ion to influence the effect of [H.sub.2]S. After examining the vasorelaxant effects of acetylcholine, a vasodilator by releasing nitric oxide, and isoprenaline, a [beta]-adrenoceptor agonist, in HEPES and Krebs buffers, we found the HC[O.sup.-.sub.3]-dependent effect was specific to [H.sub.2]S. Blockade of anion exchanger-2 activity with 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS) or with HC[O.sup.-.sub.3]-free solution abolished the vasoconstrictive effect of NaHS. Moreover, NaHS decreased nitric oxide level in the rat aorta in HC[O.sup.-.sub.3]-containing buffer, but this effect was abolished by HC[O.sup.-.sub.3]-free buffer or DIDS. In summary, we found for the first time that [H.sub.2]S stimulates anion exchanger to transport extracellular HC[O.sup.-.sub.3] in exchange for intracellular superoxide anions, which may further inactivate nitric oxide and induces vasoconstriction. anion exchanger; superoxide anions doi: 10.1152/ajpcell.00105.2010.

Phospholipase [A.sub.2] ([PLA.sub.2]), a regulatory enzyme found in most mammalian cells, catalyzes the breakdown of membrane phospholipids to arachidonic acid. There are two major cytosolic types of the enzyme, calcium-dependent ([cPLA.sub.2]) and calcium-independent ([iPLA.sub.2]) [PLA.sub.2]. The present study investigated whether or not [iPLA.sub.2] plays a role in the endothelium-dependent contractions of the aorta of the spontaneously hypertensive rat and its normotensive counterpart, the WistarKyoto rat. The presence of [iPLA.sub.2] in the endothelial cells was identified by using immunochemistry and immunoblotting. Aortic rings with and without the endothelium were suspended in organ chambers for isometric tension recording. The production of prostanoids was measured by using enzyme immunoassay kits. [iPLA.sub.2] was densely distributed in endothelial cells of the aorta of both strains. At 3 x [10.sup.-6] M, the selective [iPLA.sub.2] inhibitor, bromoenol lactone (BEL), abrogated endothelium-dependent contractions induced by acetylcholine but not those evoked by the calcium ionophore A-23187. The effects of BEL were similar in the aortae of Wistar-Kyoto and spontaneously hypertensive rats. The nonselective PLA2 inhibitor quinacrine abolished the contractions triggered by both acetylcholine and A-23187, whereas the store-operated calcium channel inhibitor SKF-96365 prevented only the acetylcholine-induced contraction. The acetylcholine- but not the A-23187-induced release of 6-keto prostaglandin [F.sub.1[alpha]] was inhibited by BEL. The release of thromboxane B2 by either acetylcholine or A-23187 was not affected by BEL. In conclusion, iPLAz plays a substantial role in the generation of endothelium-derived contracting factor evoked by acetylcholine. endothelium-derived contracting factor; prostacyclin; thromboxane [A.sub.2] doi: 10.1152/ajpheart.01068.2009.

Some pathological conditions may affect osmolarity, which can impact cell, tissue, and organ volume. The hypothesis of this study is that changes in osmolarity affect the zero-stress state and mechanical properties of the aorta. To test this hypothesis, a segment of mouse abdominal aorta was cannulated in vivo and mechanically distended by perfusion of physiological salt (NaCl) solutions with graded osmolarities from 145 to 562 mosM. The mechanical (circumferential stress, strain, and elastic modulus) and morphological (wall thickness and wall area) parameters in the loaded state were determined. To determine the osmolarity-induced changes of zero-stress state, the opening angle was observed by immersion of the sectors of mouse, rat, and pig thoracic aorta in NaCl solution with different osmolarities. Wall volume and tissue water content of the tings were also recorded at different osmolarities. Our results show that acute aortic swelling due to low osmolarity leads to an increase in wall thickness and area, a change in the stress-strain relationship, and an increase in the elastic modulus (stiffness) in mouse aorta. The opening angle, wall volume, and water content decreased significantly with increase in osmolarity. These findings suggest that acute aortic swelling and shrinking result in immediate mechanical changes in the aorta. Osmotic pressure-induced changes in the zero-stress state may serve to regulate mechanical homeostasis. swelling; opening angle; elastic modulus; strain

Endothelial dysfunction associated with elevated serum levels of TNF-[alpha] observed in diabetes, obesity, and congenital heart disease results, in part, from the impaired production of endothelial nitric oxide (NO). Cellular NO production depends absolutely on the availability of arginine, substrate of endothelial nitric oxide synthase (eNOS). In this report, evidence is provided demonstrating that treatment with TNF-[alpha] (10 ng/ml) suppresses not only eNOS expression but also the availability of arginine via the coordinate suppression of argininosuccinate synthase (AS) expression in aortic endothelial cells. Western blot and real-time RT-PCR demonstrated a significant and dose-dependent reduction of AS protein and mRNA when treated with TNF-[alpha] with a corresponding decrease in NO production. Reporter gene analysis demonstrated that TNF-[alpha] suppresses the AS proximal promoter, and EMSA analysis showed reduced binding to three essential Spl elements. Inhibitor studies suggested that the repression of AS expression by TNF-[alpha] may be mediated, in part, via the NF-[kappa]B signaling pathway. These findings demonstrate that TNF-[alpha] coordinately downregulates eNOS and AS expression, resulting in a severely impaired citrulline-NO cycle. The downregulation of AS by TNF-[alpha] is an added insult to endothelial function because of its important role in NO production and in endothelial viability. nitric oxide synthase; NF-[kappa]B; endothelial dysfunction; arginine

The present study was undertaken to determine whether neuropeptide Y (NPY) induces proliferation of rat aortic endothelial cells (RAECs). Since NPY increased the permeability of RAEC monolayers to large molecules via the NPY [Y.sub.3] receptor, RAEC proliferation has been evaluated in terms of NPY-receptor subtypes and also intracellular mechanisms. RAECs were incubated with gases containing 20, 15, or 10% [O.sub.2] and a certain amount of [N.sub.2], depending on the [O.sub.2] content in 5% C[O.sub.2] incubators. NPY ([10.sup.-9]-[10.sup.-6] M) increased the RAEC numbers under hypoxic conditions, such as 15 or 10% [O.sub.2]. Peptide YY elicited no proliferative effect on RAEC, and NPY-(18-36) inhibited the NPY-induced increase in cell number, suggesting that NPY increases the RAEC count through the NPY [Y.sub.3] receptor. Pertussis toxin, U-73122, GF-109203X, myristorylated autocamtide-2-related inhibitory peptide, and wortmannin inhibited the NPY-induced proliferation of RAEC concentration dependently. DY9760e little affected the proliferation caused by NPY. ML-9 and imatinib actually enhanced the NPY-induced proliferation of cells. These results indicated that the NPY [Y.sub.3] receptor is coupled with [G.sub.i] protein, and that NPY-induced increases in RAEC proliferation are mediated by phospholipase C-protein kinase C and/or phosphatidylinositol 3-kinase pathways. In intracellular [Ca.sup.2+]-calmodulin-dependent pathways, calmodulin-dependent protein kinase II partly participates in the NPY-induced cell proliferation. Regarding the previously reported effect of NPY on the permeability of RAEC monolayers to large molecules, it is probable that protein kinase C and phosphatidylinositol 3-kinase pathways are activated for both permeability and cell proliferation induced by NPY under hypoxia, relevant to new insights into the roles of NPY in ischemia-hypoxia. protein kinase C; phosphatidylinositol 3-kinase; phospholipase C; calmodulin-dependent protein kinase

Elastic fibers play a key role in the structure and function of numerous organs that require elasticity. Elastogenesis is a complex process in which cells first produce a microfibrillar scaffold, composed of numerous structural proteins, upon which tropoelastin assembles to be cross-linked into polymeric elastin. Recently, it was demonstrated that low concentrations of free iron upregulate elastin gene expression in cultured fibroblasts. The present studies were conducted to assess whether low-iron diets would affect the deposition of elastic fibers in an in vivo model. One-day-old chicks were fed semipurified diets containing 1.3 (low), 12 (moderate), and 24 (control) mg/kg of iron. After 3 wk, chicks in the low-iron group were underweight and anemic. Their aortas were smaller with significantly thinner walls than control chicks, yet elastin or collagen content did not decrease relative to total protein. They also demonstrated a significantly lower stress-strain resistance than the controls. Electron microscopy demonstrated that aortic and lung smooth muscle cells were vacuolated and surrounded by loose extracellular matrix and disorganized elastic lamellae with diffuse and fragmented networks of elastic fibers and microfibrils. Immunohistology demonstrated that fibrillin-3 (FBN3) was disorganized and markedly reduced in amount in aortas of the low-iron chicks. Elastin messenger RNA levels were not downregulated in the tissues from the low-iron-fed chicks; however, there was a significant reduction in expression of the FBN1 and FBN3 genes compared with control chicks. The studies indicate that iron deficiency had a pronounced negative effect on elastic fiber development and suggests that fibrillin may have an important role in this pathology.

Abstract: Aortic stiffness is thought to affect coronary blood flow, but little is known about its influence on coronary flow reserve (CFR). The objective of the present study was to [...]

ANG II stimulates the production of reactive oxygen species and activates proinflammatory cytokines leading to endothelial dysfunction. We hypothesized that the anti-inflammatory cytokine IL-10 counteracts the impairment in endothelium-dependent ACh relaxation caused by ANG II. Aortic rings of C57BL/6 mice were incubated in DMEM in the presence of vehicle (deionized H20), ANG II (100 nmol/l), recombinant mouse IL-10 (300 ng/ml), or both ANG II and IL-10 for 22 h at 37 [degrees]C. After incubation, rings were mounted in a wire myograph to assess endothelium-dependent vasorelaxation to cumulative concentrations of ACh. Overnight exposure of aortic tings to ANG II resulted in blunted ACh-induced vasorelaxation compared with that shown in untreated rings (maximal response = 44 [+ or -] 3% vs. 64 [+ or -] 3%, respectively; P < 0.05). IL-10 treatment significantly restored this impairment in relaxation (63 [+ or -] 2%). In addition, the NADPH oxidase inhibitor apocynin restored the impairment in relaxation (maximal response = 76 [+ or -] 3%). Western blotting showed increased gp[91.sup.phox] expression (a subunit of NADPH oxidase) in response to ANG II. Vessels treated with a combination of ANG II and IL-10 showed decreased expression of gp[91.sup.phox]. Immunohistochemical analysis showed increased gp[91.sup.phox] expression in ANG II-treated vessels compared with those treated with combined ANG II and IL-10. We found that the anti-inflammatory cytokine IL-10 prevents impairment in endothelium-dependent vasorelaxation in response to long-term incubation with ANG II via decreasing NADPH oxidase expression. NADPH oxidase doi: 10.1152/ajpheart.00456.2006

We investigated the quantitative contribution of all local conduit arterial, blood, and distal load properties to the pressure transfer function from brachial artery to aorta. The model was based on anatomical data, Young's modulus, wall viscosity, blood viscosity, and blood density. A three-element wind-kessel represented the distal arterial tree. Sensitivity analysis was performed in terms of frequency and magnitude of the peak of the transfer function and in terms of systolic, diastolic, and pulse pressure in the aorta. The root mean square error (RMSE) described the accuracy in wave-shape prediction. The percent change of these variables for a 25% alteration of each of the model parameters was calculated. Vessel length and diameter are found to be the most important parameters determining pressure transfer. Systolic and diastolic pressure changed blood pressure; transfer function; personalization; brachial artery; aorta

The etiology of the atherosclerosis that occurs in diabetes mellitus is unclear. Adenosine has been shown to inhibit growth of rat aortic smooth muscle cells. Nucleoside transporters play an integral role in adenosine function by regulating adenosine levels in the vicinity of adenosine receptors. Therefore, we studied the effect of 25 mM D-glucose, which mimics hyperglycemia of diabetes, on adenosine transport in cultured human aortic smooth muscle cells (HASMCs). Although RT-PCR demonstrated the presence of equilibrative nucleoside transporter-1 (ENT-1) and ENT-2 mRNA, functional studies revealed that adenosine transport in HASMCs was predominantly mediated by ENT-1 and inhibited by nitrobenzylmercaptopurine riboside (NBMPR, I[C.sub.50] = 0.69 [+ or -] 0.05 nM). Adenosine transport in HASMCs was increased by >30% after treatment for 48 h with 25 mM D-glucose, but not with equimolar D-mannitol and L-glucose. Kinetic studies showed that D-glucose increased [V.sub.max] of adenosine transport without affecting [K.sub.m]. Similarly, D-glucose increased [B.sub.max] of high-affinity [sup.3H]NBMPR binding, while the dissociation constant ([K.sub.d]) was not changed. Consistent with these observations, 25 mM D-glucose increased mRNA and protein expression of ENT-1. Treatment of serum-starved cells with the selective inhibitors of MAPK/ERK, PD-98059 (40 [micro]M) and U-0126 (10 [micro]M), abolished the effect of D-glucose on ENT-1. We conclude that D-glucose upregulates the protein and message expression and functional activity of ENT-1 in HASMCs, possibly via MAPK/ ERK-dependent pathways. Pathologically, the increase in ENT-1 activity in diabetes may affect the availability of adenosine in the vicinity of adenosine receptors and, thus, alter vascular functions in diabetes. nucleoside transporter; diabetes

We hypothesized that the inducible kinin [B.sub.1] receptor ([B.sub.1]R) is rapidly cleared from cells when its synthesis subsides. The agonist-independent degradation of the rabbit [B.sub.1]Rs and related [B.sub.2] receptors ([B.sub.2]Rs) was investigated. Endocytosis of the [B.sub.1]R-yellow fluorescent protein (YFP) conjugate was more intense than that of [B.sub.2]R-green fluorescent protein (GFP) based on fluorescence accumulation in HEK 293 cells treated with a lysosomal inhibitor. The cells expressing [B.sub.1]R-YFP contained more GFP/YFP-sized degradation product(s) than those expressing [B.sub.2]R-GFP (immunoblot, antibodies equally reacting with both fluorescent proteins). The binding site density of [B.sub.1]R-YFP decreased in the presence of protein synthesis or maturation inhibitors (anisomycin, brefeldin A), whereas that of [B.sub.2]R-GFP remained constant. Wild-type [B.sub.1]Rs were also cleared faster than [B.sub.2]Rs in rabbit smooth muscle cells treated with metabolic inhibitors. Contractility experiments based on brefeldin A-treated isolated rabbit blood vessels also functionally support that [B.sub.1]Rs are more rapidly eliminated than [B.sub.2]Rs (decreased maximal effect of agonist over 2 h). The highly regulated [B.sub.1]R is rapidly degraded, relative to the constitutive [B.sub.2]R. kinin [B.sub.2] receptor; rabbit aorta; rabbit jugular vein; smooth muscle cells

To delineate the roles that oxygen and fibroblast growth factors (FGFs) play in the process of angiogenesis from the embryonic aorta, we cultured mouse embryonic aorta explants (thoracic level to lateral vessels supplying the mesonephros and metanephros) in a three-dimensional type I collagen gel matrix. During 8 days of culture under 5% [O.sub.2], but not room air, the addition of FGF2 to explants stimulated the formation of Gs-I[B.sub.4-] positive, CD31-positive, and Flk-1-positive microvessels in a concentration-dependent manner. FGF2-stimulated microvessel formation was inhibited by sequestration of FGF2 via addition of soluble FGF receptor (FGFR) chimera protein or anti-FGF2 antibodies. FGFR1 and FGFR2 were present on explants. Levels of FGFR1, but not FGFR2, were increased in embryonic aorta cultured under 5% [O.sub.2] relative to room air. Our data suggest that low oxygen upregulates FGFR1 expression in embryonic aorta in vitro and renders it more responsive to FGF2. angiogenesis; embryogenesis; endothelial cell; organ culture

In children, aortic lipid deposition develops in triangular regions of the wall downstream of branch points, whilst in adults these regions are particularly free of disease. Comparable age-related patterns occur in rabbit aortas. They may be explained by patterns of wall permeability to circulating macromolecules: along the longitudinal midline through branches, permeability is greater downstream than upstream in immature rabbits, but is greater upstream at later ages. Here we have mapped permeability in detail around such branches, not just along the midline. Short-term uptake of rhodamine-labeled albumin, measured using digital imaging fluorescence microscopy of serial sections, was greatest in an approximately triangular region downstream of immature branches, but in mature animals it was greater upstream, particularly away from the midline, and in streaks to the side of branches. Hence the maps are consistent with earlier permeability data and closely resemble the patterns of disease. [DOI: 10.1115/1.1517063]

The goal of the present study was to obtain a systematic set of data along the length of the mouse aorta to study variations of morphometry (diameter, wall thickness, and curvature), strain, and stress of the mouse aorta. Five mice were imaged with a 13-MHz ultrasound probe to determine the in vivo diameter along the aorta. A cast was made of these aortas to validate the ultrasonic diameter measurements. The root mean squared and systematic errors for these measurements were 12.6% and 6.4% of the mean ultrasound diameter, respectively. The longitudinal variations of geometry, stress, and strain from the aortic valve to the common iliac bifurcation were documented. Our results show that the residual circumferential strain leads to a uniformity of transmural strain of the aorta in the loaded state along the entire length of the aorta. Furthermore, we validated the incompressibility condition along the length of the aorta. These data of normal mice will serve as a reference state for the study of disease in future knockout models. opening angle; zero-stress state; ultrasound; diameter; stress

In 12 mechanically ventilated and anesthetized rabbits, we investigated whether the magnitude of respiratory changes in the aortic velocity time integral (VT[I.sub.Ao]), recorded by transthoracic echocardiography (TTE) during a stepwise blood withdrawal and restitution, could be used as a reliable indicator of volume depletion and responsiveness. At each step, left and right ventricular dimensions and the aortic diameter and VT[I.sub.Ao] were recorded to calculate stroke volume (SV) and cardiac output (CO). Respiratory changes of VT[I.sub.Ao] (maximal--minimal values divided by their respective means) were calculated. The amount of blood withdrawal correlated negatively with left and right ventricular diastolic diameters, VT[I.sub.Ao], SV, and CO and correlated directly with respiratory changes of VT[I.sub.Ao]. Respiratory VT[I.sub.Ao] variations (but not other parameters) at the last blood withdrawal step was also correlated with changes in SV after blood restitution (r = 0.83, P < 0.001). In conclusion, respiratory variations in VT[I.sub.Ao] using TTE appear to be a sensitive index of blood volume depletion and restitution. This dynamic parameter predicted fluid responsiveness more reliably than static markers of cardiac preload. echocardiography; cardiopulmonary interactions; stroke volume variation; cardiac preload

Adrenomedullin (AM), a potent vasodilatory peptide, plays an important role in initiating the hyperdynamic response during the early stage of sepsis. Moreover, the reduced vascular responsiveness to AM appears to be responsible for the transition from the early, hyperdynamic to the late, hypodynamic phase of sepsis. Although the novel specific AM binding protein-1 (AMBP-1) enhances AM-mediated action in a cultured cell line, it remains to be determined whether AMBP-1 plays any role in modulating vascular responsiveness to AM during sepsis. To study this, adult male rats were subjected to sepsis by cecal ligation and puncture (CLP). The thoracic aorta was harvested for determination of AM-induced vascular relaxation. Aortic levels of AMBP-1 were determined by Western blot analysis, and AM receptor gene expression in the aortic tissue was assessed by RT-PCR. The results indicate that AMBP-1 significantly enhanced AM-induced vascular relaxation in aortic rings from sham-operated animals. Although vascular responsiveness to AM decreased at 20 h after CLP (i.e., the late, hypodynamic stage of sepsis), addition of AMBP-1 in vitro restored the vascular relaxation induced by AM. Moreover, the aortic level of AMBP-1 decreased significantly at 20 h after CLP. In contrast, AM receptor gene expression was not altered under such conditions. These results, taken together, suggest that AMBP-1 plays an important role in modulating vascular responsiveness to AM, and the reduced AMBP-1 appears to be responsible for the vascular AM hyporesponsiveness observed during the hypodynamic phase of sepsis. vasoactive peptide; complement factor H; adrenomedullin receptors; aorta; vascular relaxation; cecal ligation and puncture

We investigated the effects of thrombin on the induction of heat shock proteins (HSP) 70 and 27, and the mechanism behind the induction in aortic smooth muscle A10 cells. Thrombin increased the level of HSP27 but had little effect on the level of HSP70. Thrombin stimulated the accumulation of HSP27 dose dependently between 0.01 and 1 U/ml and cycloheximide reduced the accumulation. Thrombin stimulated an increase in the level of HSP27 mRNA and actinomycin D suppressed the thrombin-increased mRNA level. Thrombin induced the phosphorylation of p38 mitogen-activated protein kinase (MAPK). The HSP27 accumulation by thrombin was reduced by SB-203580 and PD-169316 but not by SB-202474. SB-203580 and PD-169316 suppressed the thrombin-induced phosphorylation of p38 MAPK. SB-203580 reduced the thrombin-increased level of HSP27 mRNA. Dissociation of the aggregated HSP27 to the dissociated HSP27 was induced by thrombin. Dissociation was inhibited by SB-203580. Thrombin induced the phosphorylation of HSP27 and the phosphorylation was suppressed by SB-203580. These results indicate that thrombin stimulates not only the dissociation of HSP27 but also the induction of HSP27 via p38 MAPK activation in aortic smooth muscle cells. serine protease; A20 cell; intracellular signaling

Characterizing embryonic circulatory physiology requires accurate cardiac output and flow data. Despite recent applications of high-frequency ultrasound Doppler to the study of embryonic circulation, current Doppler analysis of volumetric flow is relatively crude. To improve Doppler derivation of volumetric flow, we sought a preliminary model of the spatial velocity profile in the mouse embryonic dorsal aorta using ultrasound biomicroscopy (UBM)-Doppler data. Embryonic hematocrit is 0.05-0.10 so rheologic properties must be insignificant. Low Reynolds numbers ( cardiac development; embryonic blood flow; physiology; ultrasound

[H.sub.2]S is endogenously generated in vascular smooth muscle cells. The signal transduction pathways involved in the vascular effects of [H.sub.2]S have been unclear and were investigated in the present study. [H.sub.2]S induced a concentration-dependent relaxation of rat aortic tissues that was not affected by vascular denervation. The vasorelaxant potency of [H.sub.2]S was attenuated by the removal of the endothelium. Similarly, the blockade of nitric oxide synthase or the coapplication of the [Ca.sup.2+]-dependent [K.sup.+] channel blockers apamin and charybdotoxin reduced the [H.sub.2]S-induced relaxation of the endothelium-intact aortic tissues. Sodium nitroprusside (SNP)-induced relaxation was completely abolished by either 1H-[1,2,4]oxadiazolo-[4,3-a] quinoxalin-1-one (ODQ) or NS-2028, two soluble guanylate cyclase inhibitors. Instead of inhibition, ODQ and NS-2028 potentiated the [H.sub.2]S-induced vasorelaxation, which was suppressed by superoxide dismutase. The vasorelaxant effect of [H.sub.2]S was also significantly attenuated when [Ca.sup.2+]-free bath solution was used. Finally, pretreatment of aortic tissues with [H.sub.2]S reduced the relaxant response of vascular tissues to SNP. Our results demonstrate that the vascular effect of [H.sub.2]S is partially mediated by a functional endothelium and dependent on the extracellular calcium entry but independent of the activation of the cGMP pathway. aorta; guanosine 3',5'-cyclic monophosphate; endothelium

Expression of adenosine receptors in the preglomerular microcirculation. Am J Physiol Renal Physiol 283: F41-F51, 2002; 10.1152/ajprenal.00232.2001.--The purpose of this study was to systematically investigate the abundance of each of the adenosine receptor subtypes in the preglomerular microcirculation vs. other vascular segments and vs. the renal cortex and medulla. Rat preglomerular microvessels (PGMVs) were isolated by iron oxide loading followed by magnetic separation. For comparison, mesenteric microvessels, segments of the aorta (thoracic, middle abdominal, and lower abdominal), renal cortex, and renal medulla were obtained by dissection. Adenosine receptor protein and mRNA expression were examined by Western blotting, Northern blotting, and RT-PCR. Our results indicate that compared with other vascular segments and renal tissues, [A.sub.1] and [A.sub.2B] receptor protein and mRNA are abundantly expressed in the preglomerular microcirculation, whereas [A.sub.2A] and [A.sub.3] receptor protein and mRNA are barely detectable or undetectable in PGMVs. We conclude that, relative to other vascular and renal tissues, [A.sub.1] and [A.sub.2B] receptors are well expressed in PGMVs, whereas [A.sub.2A] and [A.sub.3] receptors are notably deficient. Thus [A.sub.1] and [A.sub.2B] receptors, but not [A.sub.2A] or [A.sub.3] receptors, may importantly regulate the preglomerular microcirculation. kidney; renal microcirculation; mesenteric microcirculation; aorta

Rat aortic endothelium is differentiated regionally for three signal pathways capable of regulating the cGMP content of the underlying smooth muscle. Formation of nitric oxide (NO) from L-arginine and of glutamate from L-leucine increase cGMP; however, formation of prostaglandin [H.sub.2] (PG[H.sub.2]) decreases cGMP. All three have peak activity in the windkessel area just distal to the aortic arch and decrease peripherally. We report evidence that the biochemical route of the leucine-to-glutamate (Leu [right arrow] Glu) pathway is via metabolism of leucine to acetyl CoA, that the controlling reaction of the pathway is mediated by the branched chain [alpha]-ketoacid dehydrogenase complex (BCDC), and that glutamate formation via the Leu [right arrow] Glu pathway is a major source of aortic segment free glutamate in vitro. Interruption of the pathway by treatment of precontracted rat aortic rings in vitro with each of three classes of inhibitors (leucine analogs, competitors for the BCDC reaction, or inhibitors of L-glutamate transport) enhances contractile responses. The enhancement requires an intact endothelium and is not owing to reductions in NO formation. The results support the hypothesis that the Leu [right arrow] Glu pathway functions in the regulation of aortic contractility and compliance. endothelium; branched-chain [alpha]-ketoacid dehydrogenase complex; aortic compliance; vascular smooth muscle; acetyl coenzyme A

Structural diversity of N-sulfated (NS) heparan sulfate (HS) domains have been studied to add to understanding of the relationship between S domain length and degree of modification. The degree of polymer change in series of size-fractionated NS domain from various HS species were determined. Findings show noticeable tissue-specific variation in the sulfation patterns of NS domains. Previously unrecognized distinctions in the coordination of the three polymer modification reactions during heparan sulfate biosynthesis were seen.

Apolipoprotein A1 depletes cholesterol from human aortic smooth muscle cells. Aortic tissue from other animals seem to be resistant to this activity, but this is not the case in humans. ApoAI is the primary protein in high-density lipoproteins (HDL).

The activity of Na+-K+-2Cl- cotransporter NKCC1 in vascular smooth muscle was measured as the bumetanide-sensitive efflux of 86Rb+ from intact smooth muscle of the rat aorta. Results showed that the Na+-K+-2Cl- cotransporter in vascular smooth muscle is reciprocally controlled by vasoconstrictors and nitrovasodilators and contributes to smooth muscle contraction, indicating that changes in NKCC1 could affect vascular smooth muscle tone in vivo.

The central and peripheral cardiovascular effects of endothelin-1 have been investigated in conscious rainbow trout. It was found that both intra-arterial and intracerebroventricular administration of endothelin-1 induced a dose-dependent increase in mean dorsal aortic blood pressure and a concomitant reduction in heart rate. The hypertensive effects generated by intracerebroventricular and intra-arterial injection of endothelin-1 were linked to a substantial increase in systemic vascular resistance.

The potential role of estrogen in altering aortic elastic properties was investigated among 20 postmenopausal women, 10 without and 10 with proven coronary artery disease before and after intravenous administration of 10 micrograms of 17beta-estradiol. Aortic distensibility increased after estrogen administration, whereas the pressure-diameter loop was shifted downward along a different hypothetical line of elasticity. These suggest active changes in the aortic elastic properties.

The possible role of activated extracellular signal-regulated kinases (ERK) 1 and 2 in enhanced proliferation and morphological change induced by strain is studied using bovine aortic endothelial cells subjected to an average of 6% or 10% strain at a rate of 60 cycles per minute for up to four hours. Findings suggest that ERK1 and ERK2 are not critically involved in the strain-induced proliferation and orientation and that strain-dependent activation of ERK1 and ERK2 is independent of intracellular and extracellular calcium mobilization.

The total arterial compliance from pressure and flow in the ascending aorta of seven anesthetized dogs was determined using the pulse pressure method and the decay time method. Results indicate that if the upper limbs and the head contribute as little as the lower limbs, 60% of total arterial compliance resides in the proximal aorta. When the inverse relationship between pressure and compliance is taken into consideration, the contribution of the proximal aorta to the total arterial compliance is even more significant.

The in situ isolation of baroreceptor regions of the carotid sinus and aortic depressor nerves of rats have been carried out with new methods. The latter do not require special materials, tools or manipulation of the baroreceptor regions. Ball bearings are used in extracting the sinus baroreceptor region while the baroreceptor area of the right aortic depressor nerve is isolated by ligation of the innominate, common carotid and right subclavian arteries.

Stress-modulated growth in the aorta is studied using a theoretical model. The model is a thick-walled tube composed of two pseudoelastic, orthotropic layers representing the intima/media and the adventitia. Both layers are assumed to follow a growth law in which the time rates of change of the growth stretch ratios depend linearly on the local smooth muscle fiber stress and on the shear stress due to blood flow on the endothelium. Using finite elasticity theory modified to include volumetric growth, we computed temporal changes in stress, geometry, and opening angle (residual strain) during development and following the onset of sudden hypertension. For appropriate values of the coefficients in the growth law, the model yields results in reasonable agreement with published data for global and local growth of the rat aorta.

Derivation of the aortic systolic and diastolic pressure from the pressure and flow measurements from peripheral vessels can be done using a transfer function that uses a time domain approach. The aortic systolic and diastolic pressures can be estimated from the hemodynamic parameters of the brachial and carotid artery. The vasoactive state of the vessels does not influence the prediction significantly.

Isolated segments of extralobar rat pulmonary artery and aorta devoid of endothelium from control subjects and from subjects exposed to hypoxic conditions were used in the investigation of the effects of hypoxia on endothelin responsiveness. Results reveal that hypoxia reduces the sensitivity of vascular smooth muscle to endothelin and this is positively correlated with the length of exposure. This reduction in endothelin sensitivity is brought about by the increase in the levels of circulating endothelin.

Research was conducted to characterize a technique for isolating in situ baroreceptor regions of the rabbit aortic depressor nerve and to study transfer functions from pressure to afferent nerve activity. The right aortic depressor curve was separated and sliced at the junction with the superior laryngeal nere and nodose ganglion under a dissecting microscope. Results showed that the gain of transduction increased as the frequency of pressure change increased from 0.01 to 2 Hz.

Research was conducted to study the function of Na+ and Ca2+ entry in the stretch-induced Na+-K+-ATPase-alpha-1 and alpha-2-isoform upregulation in rat aortic smooth muscle cells (ASMC). ASMCs were prepared from male Sprague-Dawley rats while cells were seeded on type I collagen-coated Flex I and Flex II plates. Results suggested that stretch-induced intracellular Na+ and Ca2+ changes and the resultant Na+-K+-ATPase-alpha-isoform upregulation may be important to the pathophysiology of hypertension.