The neuronal isoform of nitric oxide synthase (nNOS) is highly expressed in mammalian skeletal muscle, but its functional role has not been defined. NO has been implicated in the local metabolic regulation of blood flow in contracting skeletal muscle in part by antagonizing sympathetic vasoconstriction. We therefore hypothesized that nNOS in skeletal muscle is the source of the NO mediating the...

The stainless steel cannula inserting method was used to examine the effects of methysergide on 5-hydroxytryptamine (5-HT)- and norepinephrine-induced vasoconstriction in the isolated internal carotid artery of the dog. 5-HT, at a dose of 0.3 microgram, induced a marked increase in perfusion pressure, usually over 100 mm Hg. On the other hand, norepinephrine produced a relatively small increase...

Since indomethacin may be effective in the treatment of orthostatic hypotension, the ability of this drug to increase reflex vasoconstriction was studied in six patients with orthostatic hypotension and in five normal subjects. Reflex forearm vasoconstriction during lower body negative pressure at 20-40 mm Hg was measured before and after indomethacin 50 mg by mouth. In patients with orthostati...

Mauban, Joseph R. H., Carmelle V. Remillard, and Jason X.-J. Yuan. Hypoxic pulmonary vasoconstriction: role of ion channels. J Appl Physiol 98: 415–420, 2005. doi:10.1152/japplphysiol.00732.2004.—Acute hypoxia induces pulmonary vasoconstriction and chronic hypoxia causes structural changes of the pulmonary vasculature including arterial medial hypertrophy. Electroand pharmacomechanical mechanis...

In a number of isolated blood vessel types, hypoxia causes an acute contraction that is dependent on the presence of nitric oxide and activation of soluble guanylyl cyclase. It is more pronounced when the preparations are constricted and is therefore termed hypoxic augmentation of vasoconstriction. This hypoxic response is accompanied by increases in the intracellular level of inosine 5'-tripho...

There is a paradoxical α-adrenoceptor-mediated coronary vasoconstriction whenever there is adrenergic activation of the heart, as during cardiovascular reflexes or exercise. A previous study demonstrated that this paradoxical vasoconstriction helps maintain blood flow to the vulnerable inner layer of the left ventricular wall during exercise, but the mechanism for this effect was not elucidated...

Hypertension is associated with an elevation in agonist-induced vasoconstriction, but mechanisms involved require further investigation. Many vasoconstrictors bind to phospholipase C-coupled receptors, leading to an elevation in inositol 1,4,5-trisphosphate (IP(3)) that activates sarcoplasmic reticulum IP(3) receptors. In cerebral artery myocytes, IP(3) receptors release sarcoplasmic reticulum ...

Naik, Jay S., Lusha Xiang, and Robert L. Hester. Enhanced role for RhoA-associated kinase in adrenergic-mediated vasoconstriction in gracilis arteries from obese Zucker rats. Am J Physiol Regul Integr Comp Physiol 290: R154–R161, 2006. First published September 1, 2005; doi:10.1152/ajpregu.00245.2005.—Obesity, insulin resistance, dyslipidemia, and hypertension are components of the pathophysiol...

In the accompanying article, we showed that AP5A displayed heterogenous vasoactive effects in rat resistance arteries. It induced a stable vasoconstriction in the superior epigastric artery (SEA) and a transient vasoconstriction in the mesenteric resistance artery (MrA). In the phenylephrine-precontracted MrA AP5A induced a marked vasorelaxation. In this study the noncompetitive inhibition of t...

CONTEXT Clinical observations and case reports suggest that there are important cerebrovascular complications of cocaine use, but no studies have documented a direct link. OBJECTIVE To determine whether low-dose cocaine administration induces cerebral vasoconstriction in healthy cocaine users. DESIGN Randomized controlled trial. SUBJECTS Twenty-four healthy and neurologically normal men (...