carvedilol produced competitive antagonism of the beta 1-adrenoceptor mediated positive chronotropic response to isoproterenol in guinea pig atria , and the beta 2-adrenoceptor mediated relaxation to isoproterenol in carbachol ( 1 mumol/l ) precontracted guinea pig trachea , with a dissociation constant ( kb ) for beta 1-adrenoceptors of 0.8 nmol/l and beta 2-adrenoceptors of 1.3 nmol/l .
C1372804
positive chronotropic
C0022245
isoproterenol