Intracellular calcium increasing at the beginning of reperfusion assists the early recovery of myocardial contractility after diltiazem cardioplegia.
OBJECTIVE
We investigated the ability of diltiazem to prevent myocardial injury by assessing heart function and intracellular calcium concentrations before and after ischemia-reperfusion.


METHODS
Isolated rat hearts underwent cardioplegia using the Langendorff perfusion model and were subjected to normothermic global ischemia for 60 minutes. The recovery rates for the heart function (heart rate, coronary flow, left ventricular systolic pressure) after reperfusion were monitored, and the intracellular Ca concentration was measured during ischemia and during the following reperfusion. Experimental groups were divided into three groups according to the diltiazem concentration used in the cardioplegic solution (potassium 20 mmol/l in Ringer's solution): (1) Group A: diltiazem 2.5 mg/l; (2) Group B: diltiazem 5 mg/l; and (3) Group C: no diltiazem.


RESULTS
Intracellular calcium concentration increased in all 3 groups during ischemia, but was significantly lower in Group B compared to either Group A or Group C. The heart function was significantly higher for Group A than for Group B or Group C. The hearts in Group B displayed markedly poor recovery in contractility and in heart rate.


CONCLUSIONS
Generally, a decrease in intracellular Ca concentration improves the heart function during ischemia and after reperfusion. However, this study showed that some increase in intracellular Ca at the beginning of reperfusion assisted the contractility of rat heart.
Inoue
Koichi
K
1st Department of Surgery, School of Medicine, Showa University, Tokyo, Japan.
Ando
Susumu
S
Itagaki
Taro
T
Shiojiri
Yasuhiro
Y
Kashima
Toshitaka
T
Takaba
Toshihiro
T
D000818:Animals; D002118:Calcium / Q000032:analysis*; D002121:Calcium Channel Blockers / Q000008:administration & dosage*; D004110:Diltiazem / Q000008:administration & dosage*; D006324:Heart Arrest, Induced; D006339:Heart Rate / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D009200:Myocardial Contraction / Q000502:physiology*; D015428:Myocardial Reperfusion Injury / Q000378:metabolism / Q000503:physiopathology / Q000517:prevention & control*; D051381:Rats; D017208:Rats, Wistar
D002121:Calcium Channel Blockers; D004110:Diltiazem; D002118:Calcium