DIFFERENTIAL CHANGES IN LEFT AND RIGHT-VENTRICULAR ADENYLYL-CYCLASE ACTIVITIES IN CONGESTIVE-HEART-FAILURE

The status of beta-adrenergic receptors and adenylyl cyclase in crude membranes from both left and right ventricles was examined when the le ft coronary artery in rats was occluded for 4, 8, and 16 wk. The adeny lyl cyclase activity in the presence of isoproterenol was decreased in the uninfarcted (viable) left ventricle and increased in the right ve ntricle subsequent to myocardial infarction. The density of beta(1)-ad renergic receptors, unlike beta(2)-receptors, was reduced in the left ventricle, whereas no change in the characteristics of beta(1)- and be ta(2)-adrenergic receptors was seen in the right ventricle. The cataly tic activity of adenylyl cyclase was depressed in the viable left vent ricle but was unchanged in the right ventricle. In comparison to sham controls, the basal, as well as NaF-, forskolin-, and 5'-guanylyl imid odiphosphate [Gpp(NH)p]-stimulated adenylyl cyclase activities were de creased in the left ventricle and increased in the right ventricle of the experimental animals. Opposite alterations in the adenylyl cyclase activities in left and right ventricles from infarcted animals were a lso seen when two types of purified sarcolemmal preparations were empl oyed. These changes in adenylyl cyclase activities in the left and rig ht ventricles were dependent on the degree of heart failure. Furthermo re, adenosine 3',5'-cyclic monophosphate contents were higher in the r ight ventricle and lower in the left ventricle from infarcted animals injected with saline, isoproterenol, or forskolin in comparison to the controls. The results suggest differential changes in the viable left . and right ventricles with respect to adenylyl cyclase activities dur ing the development of congestive heart failure due to myocardial infa rction.