The Ca 2+-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 V 2 and V 3 myosin isozymes; at the higher dose of isoproterenol (0.5 mg/kg body weight) only V 1 was present. In contrast a shift toward the V 3 isozyme is present in the ventricles of Goldblatt rats. One group of rats were treated with toxic doses of digitoxin: no hypertrophy occurred but there was a disappearance of V 1 and V 2 isozymes and a 50% decrease in Ca 2+-activated ATPase activity. Thus low doses of isoproterenol produce hypertrophy with an isozyme pattern similar to that found in young (~4-6 weeks old) rats. The results with digitoxin show that shifts in the cardiac isozyme distribution can occur without hypertrophy.
|Number of pages||6|
|Journal||Archives internationales de pharmacodynamie et de therapie|
|Publication status||Published - Dec 1 1982|
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