besides mediating positive inotropic effects , right atrial beta 2 adrenoceptors may be involved in the regulation of heart rate since , in healthy volunteers , the selective beta 2-adrenoceptor antagonist , ici 118,551 , was more potent than the selective beta 1-adrenoceptor antagonist , bisoprolol , in antagonizing isoproterenol-induced tachycardia , when both antagonists were administered in doses that selectively occupied more than 90 % of beta 2 and beta 1 adrenoceptors , respectively .
C0022245
isoproterenol
C0039231
tachycardia