Effect of Methylprednisolone on Metabolism and Contractility in the Stunned Myocardium

The effect of glucocorticoid on the metabolism and contractility in the stunned myocardium was examined by phosphorus 31 nuclear magnetic resonance (31P-NMR) in Langendorff rabbit hearts by use of an artificial blood substitute, perfluorochemical emulsion Fluosol-43. After normothermic global ischemia of fifteen minutes, postischemic reperfusion of sixty-five minutes was carried out. Methylprednisolone sodium succinate (MPSS) was administered either prior to global ischemia or during postischemic reper fusion. Adenosine triphosphate (ATP), creatine phosphate (CrP), inorganic phosphate (Pi), pH, left ventricular systolic developed pressure (LV DevP) and coronary flow were continuously measured. Thirty-six hearts were divided into three experimental groups consisting of 12 hearts each; CONT consisted of controls, Pre-MPSS perfusion with MPSS containing solution (10-4M) from forty-five minutes prior to global ischemia, and Post- MPSS with the same MPSS solution immediately after postischemic reperfusion. Pre- MPSS showed a significant inhibition of the increase in Pi and of the decrease in ATP and pH during global ischemia, in comparison with the other groups, and a suppression of the overshoot of CrP observed immediately after postischemic reperfusion. LV DevP of Pre- MPSS showed a marked improvement during the postischemic reperfusion as compared with CONT. In Post-MPSS, Pi was significantly increased and ATP decreased during the postischemic reperfusion as compared with the other two groups. There were no differ ences in coronary flow during postischemic reperfusion among the three groups. In conclusion MPSS has a beneficial effect on metabolism and contractility of the stunned myocardium when it is administered prior to ischemia.