Effects of sarcoplasmic reticulum Ca2+-ATPase overexpression in postinfarction rat myocytes

Previous studies in adult myocytes isolated from rat hearts 3 wk after myocardial infarction (MI) demonstrated abnormal contractility and intracellular Ca2+ concentration ([Ca2+]i) homeostasis and decreased sarcoplasmic reticulum Ca2+-ATPase (SERCA2) expression and activity, but sarcoplasmic reticulum Ca2+ leak was unchanged. In the present study, we investigated whether SERCA2 overexpression in MI myocytes would restore contraction and [Ca2+]i transients to normal. Compared with sham-operated hearts, 3-wk MI hearts exhibited significantly higher left ventricular end-diastolic and end-systolic volumes but lower fractional shortening and ejection fraction, as measured by M-mode echocardiography. Seventy-two hours after adenovirus-mediated gene transfer, SERCA2 overexpression in 3-wk MI myocytes did not affect Na+-Ca2+ exchanger expression but restored the depressed SERCA2 levels toward those measured in sham myocytes. In addition, the reduced sarcoplasmic reticulum Ca2+ uptake in MI myocytes was improved t...