Changes in myosin isozyme distribution induced by low doses of isoproterenol.
The Ca2+-activated myosin ATPase activity in isoproterenol-induced hypertrophied left ventricle increased by 20-30% while in Goldblatt rats hypertrophy occurred with a decreased myosin ATPase activity. In non-dissociating (pyrophosphate) gel electrophoresis isoproterenol treatment showed decreased V2 and V3 myosin isozymes; at the higher dose of isoproterenol (0.5 mg/kg body weight) only V1 was present. In contrast a shift toward the V3 isozyme is present in the ventricles of Goldblatt rats. One group of rats was treated with toxic doses of digitoxin: no hypertrophy occurred but there was a disappearance of V1 and V2 isozymes and a 50% decrease in Ca2+-activated ATPase activity. Thus low doses of isoproterenol produce hypertrophy with an isozyme pattern similar to that found in young (approximately 4-6 weeks old) rats. The results with digitoxin show that shifts in the cardiac isozyme distribution can occur without hypertrophy.
D000251:Adenosine Triphosphatases / Q000032:analysis; D000818:Animals; D006332:Cardiomegaly / Q000139:chemically induced / Q000201:enzymology*; D007527:Isoenzymes / Q000032:analysis*; D007545:Isoproterenol / Q000008:administration & dosage / Q000494:pharmacology*; D009218:Myosins / Q000032:analysis*; D051381:Rats; D011919:Rats, Inbred Strains
D007527:Isoenzymes; D000251:Adenosine Triphosphatases; D009218:Myosins; D007545:Isoproterenol