Studies of the cardiac sarcoplasmic reticulum in myocardial infarction.
1. Influence of ischemia on the biochemical properties of the sarcoplasmic reticulum (SR) was studied in the experimental myocardial infarction in the dog. 2. Ca2+ -uptake rate of SR decreased at around 90 minutes after coronary occlusion. This reduction was roughly in parallel with the reduction in the Ca+ -Mg2+ -stimulated ATPase activity. However, Ca2+ -binding rate of SR was kept within the range of that of the non-infarcted tissue through the time course of myocardial infarction. 3. Ca2+ -Mg2+ -stimulated ATPase activity decreased at around 3 hours after coronary occlusion to about 50% of that of the non-infarcted portion. 4. In SDS gel electrophoresis, the protein band with the largest molecular weight among three major components decreased at 3 hours after coronary occlusion, which is suggestive of ATPase. At 48 hours after coronary occlusion, the protein with the smallest molecular weight in the major proteins also decreased. 5. Ca2+ -uptake rate, Ca2+ -Mg2+ -stimulated ATPase activity and the substructural changes return to the normal level and pattern at around 28 days after coronary occlusion.
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism; D004285:Dogs; D066298:In Vitro Techniques; D008274:Magnesium / Q000378:metabolism; D009203:Myocardial Infarction / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D012519:Sarcoplasmic Reticulum / Q000378:metabolism*
D000251:Adenosine Triphosphatases; D008274:Magnesium; D002118:Calcium