MYOCARDIAL-INFARCTION IS COUPLED WITH THE ACTIVATION OF CYCLINS AND CYCLIN-DEPENDENT KINASES IN MYOCYTES

To determine whether the molecular components implicated in the regula tion of the cell cycle are activated in myocytes after infarction, the expression of cyclins E, A, and B and the levels of their associated kinase activity were measured at 1 and 7 days following surgery. The q uantity of cdk2 and cdc2 and the level of their kinase activity were a lso determined. Myocardial infarction was characterized by an increase in cyclins E, A, and B and cdc2 proteins in the surviving myocytes at 1 and 7 days. Cyclin E, A, and B and cdk2 and cdc2 kinase activity al so increased. The quantity of cyclins E and A and the level of cyclin E-associated kinase activity in myocytes after infarction were compara ble with those measured in neonatal myocytes. Moreover, cdc2 protein a nd cdc2 kinase activity in myocytes reached levels after infarction wh ich were similar to those in neonatal myocytes. Thus, myocytes react t o myocardial infarction by activating cyclins and cyclin-dependent kin ases which may he coupled with the regeneration of muscle mass and rec overy of ventricular function. (C) 1996 Academic Press, Inc.