Lysosomal and neutral hydrolase activity during the regression of cardiac hypertrophy.

Cardiac hypertrophy was produced in rats by constriction of the ascending aorta. Removal of the constricting band 10 days after operation resulted in rapid decline in left ventricular (LV) weight and total ventricular RNA. Activities of acid RNase and beta-glucuronidase were elevated 3 days after aortic constriction. Activities of cathepsin D and alkaline RNase were unchanges. Activities of cathepsin D and acid RNase were unchanged 1 and 3 days after removal of constricting band. Ca2+-activated, neutral protease (CAF) isolated from postmitochondrial muscle supernatant was partially purified and characterized. CAF specifically degrades alpha-actinin when incubated with isolated myofibriles in the presence of Ca2+.