Chronological effects of mild pressure overload on myosin ATPase activity in the canine right ventricle

Mild pulmonic stenosis in the dog, performed by pulmonary artery banding, caused an increasing elevation in myosin ATPase activity which peaked in enzymatic V max values by 5 weeks after surgery (35% above normal) and then steadily declined; activity fell 11% below normal by 16 weeks after operation. During the postoperative period there was a consistent elevation in right ventricular peak systolic pressure, which remained approximately 60% above that of normal animals. The free wall of the right ventricle reached maximum size in wet weight by 5 weeks after pulmonic banding.