[Effects of long-term atenolol treatment on beta-adrenoceptor subtypes in rat heart].
The effects of long-term beta 1-AR selective antagonist atenolol treatment on beta-adrenoceptor subtypes were studied by radioligand binding assay, function determination and cAMP accumulation measerment in rat heart. The reasults showed that during long-term administration of atenolol: (1) The density of total beta-AR was increased by approximately 57%; the positive inotropic response and cAMP formation induced by activation of beta-AR were also enhanced. (2) The 125I-pindol competitive inhibition curve for CGP20712A showed that there were no significant difference in the percentage of beta 1- and beta 2-AR sites between the atenolol treated rats and the control rats; pA2 values for selective beta 1-AR antagonist CGP20712A and pKB values for selective beta 1-AR antagonist ICI 118, 551 were not significantly different in the two groups. The results suggested that beta 1- and beta 2-adrenoceptors were upregulated not only in density but also in positive inotropic effect to the same extent.
D000818:Animals; D001262:Atenolol / Q000009:adverse effects / Q000494:pharmacology*; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D011943:Receptors, Adrenergic, beta / Q000187:drug effects* / Q000378:metabolism; D015854:Up-Regulation
D011943:Receptors, Adrenergic, beta; D001262:Atenolol