ISSN:
1432-1041
Keywords:
methoxamine
;
B-HT 933
;
indoramin
;
yohimbine
;
alpha1-/alpha2-adrenoceptors
;
alpha-adrenergic vascular tone
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Medicine
Notes:
Summary To confirm the presence of alpha2-mediated vasoconstriction in human vasculature, the effect of selective alpha1- and alpha2-agonists (methoxamine and B-HT 933) and antagonists (indoramin and Yohimbine) was studied in fourteen patients with mild, uncomplicated, essential hypertension. Drugs were infused, into the brachial artery at systemically ineffective rates, and concomitant changes in forearm blood flow were measured by strain gauge venous plethysmography. During control conditions, cumulative infusions either of methoxamine or B-HT 933 caused dose-related vasoconstriction, while both indoramin and yohimbine doubled forearm blood flow. Subsequently, the alpha1-adrenoceptor mediated vasoconstriction produced by methoxamine was shown to be completely blocked by indoramin pretreatment, and to be left unchanged by yohimbine. The alpha2-vascular stimulation by B-HT 933 was antagonized by previous yohimbine but not by indoramin pretreatment, thus fulfilling the pharmacological requirements for identification of distinct alpha-adrenoceptor mediated excitation-contraction pathways. The data provide further evidence of the existence of alpha2-mediated vasoconstriction in human forearm vessels.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00542444
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