SHIFTS IN CONTRACTILE REGULATORY PROTEIN SUBUNITS TROPONIN-T AND TROPONIN-I IN CARDIAC-HYPERTROPHY

To examine the molecular basis of hypertrophied heart failure, we inve stigated the changes in cardiac contractile regulatory proteins. The g uinea pigs were subjected to chronic pressure overload with aortic ban ding to induce ventricular hypertrophy, and in-situ pressure-volume re lations were recorded together with biochemical characterizations to a scertain the contractile modifications. Immunoblots of left and right ventricular samples revealed four distinct troponin T isoforms, which underwent alterations during hypertrophy. The higher molecular weight bands TnT1 and TnT2 shifted towards the lower molecular weight isoform s TnT3 and TnT4. For TnI, a single prominent band was detected, whose intensity also increased with pump failure. The findings provide the f irst direct evidence of TnT and TnI shifts in an experimentally induce d hypertrophied heart failure and has novel mechanistic implications f or the future studies. (C) 1994 Academic Press, Inc.