Changes in cAMP concentrations during chronic cardiac hypertrophy.

Mild pulmonic stenosis in the dog, where right ventricular peak systolic pressure was increased approximately 150% at the time of sacrifice, induced 100% or more increase in right ventricular free wall weight by 3 weeks postoperative. Accompanying cardiac hypertrophy at these postoperative times, there was a decrease in both tissue PO2 levels and cAMP concentrations in the hemodynamically stressed ventricle, the right ventricle. Myosin ATPase activity was elevated as well as the velocity of contractile element shortening. The hemodynamically nonstressed left ventricle did not hypertrophy at these early postoperative times.