Turnover rates and synthesis of cardiac structural proteins in normal and hypertrophied heart.

Turnover rates and synthesis of cardiac structural proteins were studied in normal and hypertrophied rabbit heart. The order of incorporation rates of radioactive lysine in normal heart was: left ventricular greater than right ventricular greater than atrial greater than skeletal myosin B. In left ventricular muscle, the order of relative turnover rates of structural proteins was: native tropomyosin greater than the complex of 10 S-actinin and alpha-actinin greater than myosin heavy chain greater than myosin light chain greater than (soluble protein) greater than actin. After aortic constriction (to three-fourths of its original circumference), the rates of incorporation of radioactive lysine into each structural protein fraction increased, reaching a peak on the 7th day. The values returned to the levels of the normal group after 1 month. It was noted that the increase of incorporation into native tropomyosin was greater than the other structural proteins 7 days after constriction.