Differential changes in left and right ventricular SR calcium transport in congestive heart failure.
To examine the status of sarcoplasmic reticulum (SR) with respect to Ca2+ transport in congestive heart failure due to myocardial infarction, the left coronary artery in rats was ligated for 4, 8, and 16 wk. The left heart function was assessed with an intraventricular pressure transducer, and SR membrane fractions from the right ventricle and the viable left ventricle were isolated for measuring the ATP-dependent Ca2+ uptake activities. In comparison to sham-operated controls, SR Ca2+ uptake activity was decreased in viable left ventricle of the experimental animals at 4, 8, and 16 wk. On the other hand, SR Ca2+ uptake activity in the right ventricle was increased at 4 and 8 wk, but no change was apparent at 16 wk of coronary occlusion. The decrease in SR Ca2+ uptake in left ventricle and increase in right ventricle were associated with corresponding changes in maximal velocity values without any alterations in the affinity for Ca2+. These opposite changes in the right and left ventricles were dependent on the scar size as well as time after inducing the myocardial infarction. The SR Ca(2+)-stimulated adenosinetriphosphatase activity was decreased in left ventricle and increased in the right ventricle from 4 wk experimental animals. The results suggest differential remodeling of the SR membranes with respect to Ca(2+)-pump mechanisms in left and right ventricles during the development of congestive heart failure.
Afzal
N
N
Division of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, Winnipeg, Manitoba, Canada.
Dhalla
N S
NS
D000818:Animals; D001794:Blood Pressure; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D003331:Coronary Vessels / Q000502:physiology; D003576:Electron Transport Complex IV / Q000378:metabolism; D005952:Glucose-6-Phosphatase / Q000378:metabolism; D006333:Heart Failure / Q000378:metabolism / Q000503:physiopathology*; D006334:Heart Function Tests; D006339:Heart Rate; D006352:Heart Ventricles; D008297:Male; D009200:Myocardial Contraction; D009203:Myocardial Infarction / Q000378:metabolism / Q000503:physiopathology*; D009251:NADPH-Ferrihemoprotein Reductase / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D012016:Reference Values; D012519:Sarcoplasmic Reticulum / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D013997:Time Factors
D009251:NADPH-Ferrihemoprotein Reductase; D003576:Electron Transport Complex IV; D005952:Glucose-6-Phosphatase; D000252:Calcium-Transporting ATPases; D000254:Sodium-Potassium-Exchanging ATPase; D002118:Calcium