Endothelial dysfunction is the hallmark of hypertension, which is a multifactorial disorder. In the cardiovascular system reactive oxygen species play a pivotal role in controlling the endothelial function and vascular tone. Physiologically, the endothelium-derived relaxing factors (EDRFs) and endothelium-derived contractile factors (EDCFs) that have functions on the vascular smooth muscle cell...

OBJECTIVE The purpose of this study was to investigate whether the altered vascular resistance in pregnancy and preeclampsia results from alterations in intrinsic vascular smooth muscle properties or from external influences on vascular smooth muscle function. STUDY DESIGN We studied subcutaneous resistance arteries from women with preeclampsia, from normal pregnant women, and from nonpregnan...

To examine whether endothelial nitric oxide formation contributes to the vascular tone of resistance coronary vessels in vivo, we administered NG-nitro-L-arginine methyl ester (L-NAME) (10 and 100 micrograms/kg/min), a nitric oxide synthase inhibitor, as well as D-enantiomer into the left circumflex artery in normal dogs. Intracoronary L-NAME, which was associated with dose-related reductions i...

The historical demonstration by Furchgott and Zawadzki that removal of the endothelium abrogates the in vitro vasodilator effect of acetylcholine has led to the identification 30 years ago of nitric oxide (NO) as a major endogenous local regulator of vascular tone. When the ability of endothelial cells to produce NO is blunted, the ensuing vascular dysfunction sets the stage for the occurrence ...

BACKGROUND AND PURPOSE We investigated the effect of different periods of ischemia on the myogenic tone of middle cerebral arteries (MCAs) and tested the hypothesis that ischemia disrupts the actin cytoskeleton in vascular smooth muscle. METHODS The MCA occlusion model was used in male Wistar rats (n=27) to induce different periods of ischemia (15, 30, and 120 minutes) with 24 hours of reperf...

Sphingosine-1-phosphate (S1P), which mediates pleiotropic actions within the vascular system, is a prominent regulator of microvascular tone. By virtue of its S1P-degrading function, we hypothesized that S1P-phosphohydrolase 1 (SPP1) is an important regulator of tone in resistance arteries. Hamster gracilis muscle resistance arteries express mRNA encoding SPP1. Overexpression of SPP1 (via trans...

The endothelium plays a pivotal role in vascular homeostasis, regulating the tone of the vascular wall, and its interaction with circulating blood elements. Alterations in endothelial functions facilitate the infiltration of inflammatory cells and permit vascular smooth muscle proliferation and by gest on O cber 7, 2017 http://circhajournals.org/ D ow nladed from

Rhododendron dauricum L. is an ancient Chinese traditional herb. The pharmacological effects of R. dauricum extract have been shown in chronic tracheitis. The aim of this study was to investigate the cardiovascular effects of Rhododendron dauricum L. flavonoids (RF) on rats and its mechanisms. This study was performed in isolated vascular rings and a rat model of myocardial infarction and isola...

The mechanisms underlying vascular adaptations in pregnancy remain to be fully elucidated. One of the contributory mechanisms for reduced vascular tone may be a reduction of myogenic tone. Myogenic tone was assessed as the difference between internal diameter in the presence and absence of external calcium at different intramural pressure steps (60-100 mmHg). Myogenic responses were reduced in ...

Responses to vagal stimulation and acetylcholine were investigated in the feline pulmonary vascular bed under conditions of controlled pulmonary blood flow and constant left atrial pressure. Under baseline conditions, electrical stimulation of vagal efferent fibers increases lobar arterial pressure. However, when vasoconstrictor tone was increased, a depressor response was unmasked. The pressor...