Effect of acidosis on Ca2+ sensitivity of skinned cardiac muscle with troponin C exchange. Implications for myocardial ischemia.
By using a novel approach for the study of the effects of pH variation in skinned myocardium, the present experiments were aimed to provide new insights into the mechanism of ischemia. Ca2+ sensitivity is decreased by acid pH, but the effect is more than double in cardiac myofilaments than that in fast-twitch skeletal muscle fibers. With the technique of troponin C exchange in myocytes, we find here that the effect of pH is the same with cardiac or skeletal troponin C. These results rule out a direct H+-Ca2+ competition on the Ca2+-binding sites of troponin C as a significant mechanism of ischemia. The findings provide conclusive evidence in favor of the idea that acidosis modulates the protein-protein interactions in the regulatory complex in cardiac muscle.
Gulati
J
J
Department of Medicine, Albert Einstein College of Medicine, Bronx, NY 10461.
Babu
A
A
D000818:Animals; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology*; D003327:Coronary Disease / Q000378:metabolism*; D006224:Cricetinae; D006321:Heart / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D008647:Mesocricetus; D009206:Myocardium / Q000378:metabolism* / Q000473:pathology; D012518:Sarcomeres / Q000473:pathology; D014336:Troponin / Q000378:metabolism*; D019209:Troponin C
D014336:Troponin; D019209:Troponin C; D002118:Calcium