ISSN:
1432-1041
Keywords:
beta-antagonists
;
beta2-adrenoceptor
;
selectivity
;
intrinsic sympathomimetic activity
;
adrenaline hypokalaemia
;
vasidilatation
;
receptor up-regulation
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Medicine
Notes:
Summary We have examined the effects of 7 days treatment with beta adrenoceptor antagonists in 8 healthy volunteers in a placebo controlled, crossover study. We investigated three beta-adrenoceptor antagonists (atenolol, oxprenolol, and propranolol), which have differing profiles of selectivity and partial agonist properties (intrinsic sympathomimetic activity, ISA). We studied adrenaline-induced hypokalaemia, the vasodilator response to an infusion of adrenaline (0.06 µg·kg−1·min−1 for 90 min), and lymphocyte beta2-adrenoceptor number, determined by (-) [125I]-iodocyanopindolol binding, and measured these variables both before and after 7 days of treatment. The beta2-mediated depressor response to adrenaline infusion was abolished by propranolol and oxprenolol but persisted after atenolol. In contrast, the hypokalaemia induced by adrenaline was abolished by all three beta-blockers. Lymphocyte beta2-adrenoceptor number increased significantly following propranolol treatment, but not after oxprenolol for atenolol. We conclude that up-regulation of lymphocyte beta2-adrenoceptors is dependent on beta2-receptor blockade and is modified by ISA. The reversal of the hypokalaemic response by atenolol suggests that beta1 receptors may contribute to the former effect. Alternatively, since different populations of beta2-adrenoceptors differ in their susceptibility to antagonists there may also be differences in agonist coupling to beta2-responses between tissues.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00607569
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