Myocardial responsiveness to isoproterenol and calcium: a comparison of SD and F344 rats.
1. Inotropic effects of isoproterenol and extracellular Ca2+ were compared in left atrial muscle isolated from F344 and SD rats. Preparations from the F344 strain were more sensitive to the actions of both agents. 2. The chronotropic action of isoproterenol was not different in right atria isolated from the two strains. 3. This suggests that the strain-related difference in responsiveness to the inotropic effect of isoproterenol is not caused by heterogeneity in the beta-adrenoceptor/adenylate cyclase system but rather by variations in excitation-contraction coupling.
D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D006321:Heart / Q000187:drug effects*; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology*; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D009200:Myocardial Contraction / Q000187:drug effects*; D051381:Rats; D011916:Rats, Inbred F344; D011919:Rats, Inbred Strains; D013045:Species Specificity
D007545:Isoproterenol; D002118:Calcium