Mitochondrial respiration in myocardial biopsy samples as a criterion of postischemic recovery of the cardiac contractility.

Isolated perfused guinea pig hearts were arrested by a high K+ cardioplegic solution containing (PG group) or lacking (control group) 10 mM phosphocreatine + 15 mM glutamate. Total normothermic ischemia lasted 45 min followed by 30 min reperfusion. Mitochondrial respiration in the absence and presence of different concentrations of ADP and creatine was studied in biopsy samples (6-8 mg) after saponin treatment. The samples were taken before and after ischemia, as well as after the reperfusion period. A slightly better relative recovery of developed pressure (RRDP) in PG group was associated with higher mitochondrial acceptor control ratio after reperfusion (5.74 +/- 0.32 vs. 4.54 +/- 0.21 in PG and control groups, resp., p less than 0.01). When the results obtained in both groups were treated together, tight correlations between the pre- or postischemic mitochondrial state and RRDP were revealed. Higher values of RRDP were found for the hearts with lower preischemic values of (low ADP + creatine)-stimulation of mitochondrial respiration (r = -0.57, p less than 0.01). Relative changes in this mitochondrial parameter during ischemic period were in a good correlation with the RRDP (r = 0.82, p less than 0.001). The data suggest that the study of the mitochondrial function in myocardial biopsy samples before ischemia and reperfusion could provide a useful information for the prognosis of cardiac function recovery.