Analysis of pr- ram of porcine cardiac ischemia and the recovery process in coronary arterial occlusion and recanalization using 31P-MRS

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In an attempt to define the metabolic abnormalities of ischemic myocardium, the changes in high energy phoshates, inorganic phosphate and intracellular pH were serially and quantitatively evealuated in ischemic porcine hearts habing no collateral circulation using arterial pressure and respiration gated in vivo 31P magnetic resonance spectroscopy. The protocol was also modified for propranolol pretreatment (o.6mg/kg i.v.) and carteolol pre-and post-treatment (10mug/kg i.v.) as beta-blockers and verapamil (200mug/kg) to define their effects on the metabollsm of ischemic myocardium. In the non-treated group, creatine phosphate was repidly depleted by 20 miutes after ischemia; by 40 minutes, ATP and inttacellular pH gradually decreased to 10 11% of control and to 5.90 0.26, respectively, and inorganic phosphate rose to 303 43% of control. In the propranolol, and verapamil and carteolol pre-treated-group, the concentrations of ATP were higher at 20 minute occlusion, and the protective effect disappeared at 40 minute occlusion. There was no significant difference of double product between control and treated groups. This suggests that the beneficial effect of beta-blocker and Ca antagonist on ischemic myocardium is due to direct effect to viable ischemic myocytes. In reperfusion after 20 minute occlusion, creatine phosphate, pH and inorganic phosphate were normalized rapidly. In control and post treated group, ATP level did not change ecen in 120 minute reperfusion. In pretreated group, however, the concentration of ATP was normalized after 120 minute of reperfusion. This suggested that the beneficial effect is due to the protective effect during occlusion.