The pharmacological characteristics of the postjunctional alpha-adrenoceptors of vascular smooth muscle were studied in ring segments of thoracic aorta, superior mesenteric, and central ear arteries of 4- and 8-week-old, and young adult (12- to 16-week-old) rabbits. Norepinephrine (alpha 1, alpha 2-agonist), phenylephrine (alpha 1-agonist), and UK 14,304-18 (alpha 1-agonist) caused a concentrat...

Sustained stimulation of the b -adrenoceptor leads to a desensitization of the receptor-mediated adenylyl cyclase stimulation. While 2 desensitization promoted by nanomolar concentrations of isoproterenol involves the phosphorylation of the b -adrenoceptor by protein 2 kinase A alone, both protein kinase Aand b-adrenoceptor kinase-mediated phosphorylation leading to the binding of b-arrestin co...

Introduction: In recent study both endothelium-dependent and endothelium-independent mechanisms have been reported for the action of β-adrenoceptor. The aim of this study was to investigate on the role of nitric oxide (NO) and cyclic guanosin monophosphate (cGMP) in vasodilation mechanisms of β2-adrenoceptors (β2-AR) in rat skin vessels. Methods: All drugs were injected subcutaneous into p...

We have used a sensitive new technique to assess the mechanism(s) of adrenergic inhibition of rainbow trout (Oncorhynchus mykiss) red blood cell (RBC) carbon dioxide excretion in vitro. The effect was only apparent using blood acidified to simulate metabolic acidosis. Red blood cell CO2 excretion was inhibited in a dose-dependent manner by physiologically relevant concentrations of noradrenalin...

It has previously been shown that chronic inflammation causes a reduction in sympathetic nerve-mediated vasoconstriction in rat knees. To determine whether this phenomenon is due to an alteration in smooth muscle adrenoceptor function, the present study compared the alpha-adrenoceptor profile of blood vessels supplying the anteromedial capsule of normal and chronically inflamed rat knee joints....

McDougall, Jason J. Abrogation of a-adrenergic vasoactivity in chronically inflamed rat knee joints. Am J Physiol Regulatory Integrative Comp Physiol 281: R821–R827, 2001.— It has previously been shown that chronic inflammation causes a reduction in sympathetic nerve-mediated vasoconstriction in rat knees. To determine whether this phenomenon is due to an alteration in smooth muscle adrenocepto...

Hyperhomocysteinemia is a known risk factor for cardiovascular diseases, but the underlying mechanisms of this pathology are complex. We aimed to evaluate the effect of hyperhomocysteinemia in vasorelaxations induced by alpha(1D)-adrenoceptor agonists. Vascular reactivity of rat carotid artery to the alpha-adrenoceptor agonist, phenylephrine, was enhanced in hyperhomocysteinemia. Mechanical rem...

The ob gene product is known to control food intake and energy expenditure. To determine whether thermogenic agents directly control ob gene expression, the effects of beta-adrenoceptor agonists on the level of the ob gene messenger RNA (mRNA) and on leptin secretion have been studied in mouse brown adipocytes differentiated in culture. These cells highly expressed the beta 3-adrenoceptor, the ...

In this study, the ability of the nonselective adenosine receptor antagonist caffeine to influence the concentration of noradrenaline in the central nervous system was investigated, and its effects compared with those of alpha-2 adrenoceptor modulation. The technique of microdialysis in association with microbore high-performance liquid chromatography and electrochemical detection was used to m...

we studied the effect of the selective alha-2 adrenoceptor blocker idazoxan and precursor serotonin (5-htp) on anxiety-related behavior in rats. the conflict drinking test, and evaluator plus-maze were used as model. idazoxan (2 mg/kg) showed an anticonflict effect, having doses dependently increased the number of punished lickes. 5-htp showed that anxiolytic-like effect in both models. this dr...