Are beta-adrenergic receptors in ventricular muscles of carp heart (Cyprinus carpio) mostly the beta-2 type?

The positive inotropic effect of isoproterenol was quantified in the presence of several beta-adrenergic blocking agents in ventricular strips of carp heart. Isoproterenol had a concentration-dependent positive inotropic effect. The effect was markedly inhibited by propranolol and carteolol, but was extremely insensitive to atenolol. Practolol totally failed to alter the effect. These results indicated that the positive inotropic effect of isoproterenol may be mediated by mostly beta-2 adrenergic receptors in ventricular strips of carp heart.