Experimental studies on ischemic injury and reperfusion injury to the cardiac sarcoplasmic reticulum--the myocardial protective effect of nicorandil.
Ischemic and reperfusion injuries to the myocardium were evaluated by measuring cardiac function and the calcium binding capacity of the sarcoplasmic reticulum (SR) and by studying the myocardial protective effect of nicorandil. While undergoing cardiopulmonary bypass, dogs were subjected to 120-min global myocardial ischemia and then to 120-min reperfusion. Group I hearts were arrested with untreated potassium cardioplegic solution; Group II with the same solution containing 2 mg/L and Group III with the same plus 10 mg/L of nicorandil. Group III exhibited better recovery from ischemic and reperfusion injuries than Group I with recovery rates of LV dp/dt max (95.0 +/- 28.9% vs 61.1 +/- 30.4, p less than 0.05) and LV negative dp/dt max (69.0 +/- 12.5% vs 46.8 +/- 21.7, p less than 0.05). The 3 groups showed a marked decrease in the max calcium binding capacity during ischemia compared with the Control Group but exhibited no further decrease after reperfusion. After ischemia and reperfusion, Group III (30.4 +/- 9.13 nmol Ca/mg protein, 30.0 +/- 8.50) demonstrated a significantly higher binding capacity than Group I (17.0 +/- 2.41 and 18.3 +/- 1.01, p less than 0.05), while Group II did not. These results suggest that ischemia is more injurious to the calcium binding capacity of SR than reperfusion and that 10 mg/L of nicorandil added to the cardioplegic solution preserves SR function and enhances the recovery of cardiac function.
Irié
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Department of Surgery, Okayama University Medical School, Japan.
D000818:Animals; D001794:Blood Pressure; D002118:Calcium / Q000378:metabolism; D002302:Cardiac Output; D002314:Cardioplegic Solutions / Q000627:therapeutic use*; D002315:Cardiopulmonary Bypass; D003327:Coronary Disease / Q000503:physiopathology*; D004285:Dogs; D006339:Heart Rate; D015425:Myocardial Reperfusion; D015428:Myocardial Reperfusion Injury / Q000503:physiopathology*; D009206:Myocardium / Q000378:metabolism; D009536:Niacinamide / Q000031:analogs & derivatives* / Q000627:therapeutic use; D020108:Nicorandil; D012519:Sarcoplasmic Reticulum / Q000378:metabolism / Q000473:pathology*
D002314:Cardioplegic Solutions; D009536:Niacinamide; D020108:Nicorandil; D002118:Calcium