标题：Effects of Chronic Administration of Bopindolol on the Binding Characteristics of Cardiac α1H-, α1L-, β1- and β2-Adrenoceptor Subtypes in Cardiac Muscles of Spontaneously Hypertensive Rats (SHR)
摘要：The effects of the chronic administration of bopindolol on the binding characteristics of [3H]CGP12177 and [3H]prazosin to cardiac α1H-, α1L-, β1- and β2-adrenoceptor subtypes of spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY) were compared with those of two other β-blockers, atenolol and propranolol. Bopindolol (1 and 3 mg/kg/d), atenolol (50 mg/kg/d) and propranolol (60 mg/kg/d) were given to 10-week-old SHR for 12 weeks. The changes in Kd and Bmax values of the myocardium of SHR treated without and with those drugs were assessed by Scatchard analysis, and the ratio and Bmax values of the β1- and β2-adrenoceptor subtypes were also calculated from displacemental curves using ICI 118, 551. The systolic blood pressure in SHR was dose-dependently lowered by the administration of dopindolol, and was also lowered by the administration of atenolol and propranolol. The Bmax values of β1- and β2-adrenoceptors were lowered by the administration of bopindolol (1 and 3 mg/kg/d) without any changes in the Kd values or the ratio of β1- and β2-adrenoceptors. Propranolol lowered 3-fold the affinity to the β-adrenoceptor. On the other hand, the Kd and Bmax values of α1H- and α1L-adrenoceptor subtypes (high and low affinity binding sites for [3H]prazosin) were not changed by these drugs. These findings suggest that bopidolol had a beneficial effect on β-adrenoceptors in the membranes of cardiac muscles of SHR, simplying that these effects may contribute to lowering hypertension.
关键词：bopindolol;spontaneously hypertensive rat (SHR);blood pressure;α1-adrenoceptor;β-adrenoceptor;radioligand binding assay
