Ventricular myosin and creatine-kinase isoenzymes in hypertensive rats treated with captopril.

In the myocardium, myosin and creatine kinase isoforms possess different capacities for using O2 and energy-rich phosphates. We studied electrophoretically the distribution of these isoforms in 19 hypertensive rats (two-kidney, one clip model of hypertension) and in age-matched controls. After 6 weeks of hypertension, seven rats were treated with captopril (2 mg/kg daily) for 4 weeks, six were left hypertensive for another 4 weeks, and the remaining rats were killed under ether anesthesia. In the latter, ventricular mass was significantly higher than in controls; V3 isomyosin was 32.3±6.8% versus 0%, and both creatine kinase-MB and -BB were increased at the expense of creatine kinase-MM (creatine kinase-MB=29±2.8% vs. 14.7±1.8%, p<0.001; creatine kinase-BB=3.1±0.6% vs. 1.7±0.8%,m p<0.001). After 10 weeks of hypertension, ventricular mass, V3 isomyosin, and both creatine kinase-MB and -BB isoforms were fond to be persistently higher than in controls. At the same time, captopril-treated rats showed reduced but not normalized blood pressure levels, normalized ventricular mass, and prevalence of the V1 isomyosin (56.9±22% vs. 47.9±23.8% in normotensive controls, p=NS). However, higher levels of creatine kinase-MB and -BB were still found in these rats in comparison with the normotensive controls (creatine kinase-MB=22.4±5.4% vs. 15.8±2.8%, p<0.025; creatine kinase-BB=2.3±0.1% vs. 1.8±0.3%, p<0.02). Therefore, despite the normalization in ventricular mass and isomyosin pattern, captopril-treated rats partly maintain the adpative changes in creatine kinase isoenzymes that lead to a better use of energy-rich phosphates.