THE BETA-ADRENERGIC-RECEPTOR ADENYLATE-CYCLASE SYSTEM IN THE CARDIAC VENTRICLES OF A HYPERTROPHIC CARDIOMYOPATHY RAT MODEL

The WKY/NCrj rat strain is considered to be a good animal model for hypertrophic cardiomyopathy (HCM). The purpose of this study was to examine the beta-adrenergic receptor/adenylate cyclase system in the cardiac ventricles of these rats. Beta-adrenergic receptor density (Bmax) in the right ventricle (RV) was higher in WKY/NCrj than in Wistar rats. In contrast, Bmax in the interventricular septum (IVS) was lower in WKY/NCrj than in Wistar rats. Isoproterenol-stimulated adenylate cyclase activity in cardiac ventricular slices showed that changes corresponded to the changes of Bmax in every type of studied cardiac ventricle. The intracellular adenylate cyclase pathway (GTP-gamma S-, NaF- and forskolin-stimulated adenylate cyclase activity in cardiac ventricular particulate fraction) did not differ between WKY/NCrj and Wistar rats in any region of the cardiac ventricles. Catecholamine levels tended to be low in the RV and to increase in the IVS of WKY/NCrj rats. Our results suggest that the activity of the beta-adrenergic receptor/adenylate cyclase system varies in different cardiac ventricles of the WKY/NCrj rat model for HCM.