The use of quantitative coronary angiography, combined with Doppler and PET, has recently been directed at the study of alpha-adrenergic coronary vasomotion in humans. Confirming prior animal experiments, there is no evidence of alpha-adrenergic coronary constrictor tone at rest. Again confirming prior experiments, responses to alpha-adrenoceptor activation are augmented in the presence of coro...

Many studies have suggested that alpha-adrenergic receptors on vascular smooth muscle are heterogeneous and that both alpha 1- and alpha 2-adrenergic receptors can cause vasoconstriction when stimulated. We explored this hypothesis in normal humans by comparing the capacity of yohimbine, an alpha 2-adrenergic receptor antagonist, and prazosin, an alpha 1-adrenergic receptor agonist, with differ...

The ability of estrogen to increase the alpha-1 adrenergic sensitivity of rabbit uterine smooth muscle was compared with its effects on the concentration of alpha adrenoceptor subtypes in myometrium. Compared to ovariectomized controls, estrogen treatment was found to increase the adrenergic contractile sensitivity of rabbit uterus determined in vitro. Estrogen treatment increased uterine alpha...

Although peptic ulcer disease has long been recognized, the proposed mechanisms of its etiopathogenesis change every year. This review shows that gastric ulcers have a significant relationship with alpha-2 adrenergic receptors. The aggravating factors of gastric ulcer formation have been reported to act by blocking alpha-2 adrenergic receptors, whereas drugs possessing anti-ulcer activity have ...

Attenuation of sympathetic vasoconstriction (sympatholysis) in working muscles during dynamic exercise is controversial. A potential mechanism is a reduction in alpha-adrenergic-receptor responsiveness. The purpose of this study was to examine alpha(1)- and alpha(2)-adrenergic-receptor-mediated vasoconstriction in resting and exercising skeletal muscle using intra-arterial infusions of selectiv...

Alpha(2)-adrenergic receptors mediate part of the diverse biological effects of the endogenous catecholamines epinephrine and norepinephrine. Three distinct subtypes of alpha(2)-adrenergic receptors, alpha(2A), alpha(2B), alpha(2C), have been identified from multiple species. Because of the lack of sufficiently subtype-selective ligands, the specific biological functions of these receptor subty...

BACKGROUND Both alpha(2)-adrenergic and non--alpha(2)-adrenergic mechanisms seem to be involved in the hypotensive effect of imidazoline-like drugs. This study aimed at investigating how these 2 mechanisms work together to modify blood pressure (BP). METHODS AND RESULTS LNP 509, which appeared in this study to be devoid of alpha(2A)-adrenergic activity, was administered to anesthetized rabbit...

The involvement of supraspinal alpha-adrenergic receptors in tonic pain was assessed in formalin-induced pain in rats. The alpha2 adrenoceptor agonist clonidine, along with yohimbine and prazosin, α2 and α1 receptor antagonists, were introduced intracerebroventrically (icv) and/or systemically in different doses. The data show that 1) clonidine exerts an alpha adrenergic analgesic effect, ...

Norepinephrine is known to inhibit its own release from presynaptic nerve terminals through alpha 2-adrenergic receptors, which presumably have a presynaptic localization. alpha 2-Adrenergic receptors (as determined by [3H]clonidine binding) appear in rat submandibular gland membranes following reserpine treatment. These alpha 2 receptors seem to be localized postsynaptically, based on the foll...