The differential effects of a selective kappa-opioid receptor agonist, U50488, in guinea pig heart tissues.

ABSTRACT: The differential effects of a selective kappa- (κ-) opioid receptor agonist, U50488, were elucidated by monitoring the contraction of isolated guinea pig atrial and ventricular muscles. In electrically driven left atria, U50488 in nanomolar concentration range decreased the contractile force. Norbinaltorphimine (norBNI), a selective κ-receptor antagonist, and pertussis toxin (PTX) abolished the negative inotropic effect of U50488. In contrast, the inhibitory effect was not affected by the pretreatment of atropine or propranolol. Even though U50488 exerted a negative inotropic effect in the left atrium, it did not affect the contractile force of the right atrium and ventricles paced at 2 Hz. Similarly, the beating rate of the spontaneously beating right atrium was also unaffected by U50488.

SUBMITTER: Hung CF 

PROVIDER: S-EPMC4359854 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature