EFFECT OF DILTIAZEM, A CALCIUM-ANTAGONIST, ON MYOCARDIAL PH IN ISCHEMIC CANINE HEART

  • 1 January 1982
    • journal article
    • research article
    • Vol. 222  (3) , 720-725
Abstract
The effect of diltiazem on ischemic myocardial acidosis was studied in the canine heart whose left anterior descending coronary artery was partially occluded to reduce coronary flow to .apprx. 1/3 (partial occlusion). Myocardial pH was measured by use of a micro glass pH electrode. The pH decreased from 7.53 to 6.93 by partial occlusion and appeared to reach a steady state within 30 min. Saline or drugs were injected i.v. 30 min after partial occlusion. The decreased pH increased spontaneously by 34% of the total reduction of pH in the next 60 min after saline injection. Diltiazem (100 .mu.g/kg) potentiated the increase in pH; the pH increased by 76% at 60 min after the injection. Propranolol (1 mg/kg) also potentiated the increase in pH that had been decreased by partial occlusion. The relation between pH decrease and the tissue levels of metabolites was also studied. The reduction of myocardial pH from 7.5 to 6.8 was accompanied by a 2-fold increase in the tissue lactate content and by decreases in the ATP and creatine phosphate contents. There was a significant correlation between the H+ concentration calculated from the pH and each of the lactate, ATP and creatine phosphate contents. Apparently, diltiazem attenuates ischemic myocardial acidosis.