Effects of a Benzothiazepine Calcium Blocker on Electrolyte Alteration in Human Ischemic and Reperfused Myocardium

Intracellular electrotype alterations of the myocardial cells from the patients pretreated and non-treated with diltiazem in coronary surgery were measured by means of X-ray microanalysis. Myocardial biopsy specimens were obtained at the right atrial at non-ischemia, ischemia and reperfusion periods. The ion concentrations at non-ischemia which is the condition of pre-open heart surgery in patients were: Ca 0.8 ± 0.05, K 108 ± 2.3, Na 10 ± 1.9, Cl 30 ± 1 (mean ± S.E., mmol/kg wet weight, n =100-130), and there were no significant differences for Ca, K, Na and Cl with diltiazem administration. The intracellular Ca increased without diltiazem in reperfusion after open surgery. However, there was no Ca increase in either the ischemia or reperfusion states with diltiazem. The K content was significantly lower, and the Na and Cl contents were higher than those of non-ischemia in both ischemia and reperfusion without diltiazem. The K loss, and Na and Cl increases in the reperfusion period were recovered to the levels in the non-ischemia state with diltiazem administration. This study showed that the use of calcium-free cardioplegic solution caused intracellular calcium accumulation in a hypothermic global ischemic and reperfused conditions during coronary surgery, whereas, diltiazem could suppress the calcium accumulation. The alterations of potassium, sodium and chlorine were also favourable in patients with diltiazem. The possible mechanism of the effects of diltiazem on the element alterations of myocardium are discussed.