[Additional myocardial protection by normothermic cardioplegic reperfusion]

Three series of experiments were conducted on a model of an isolated working rat heart to study the efficacy of variants of cardioplegic myocardial protection in exposure to 30-minute total ischemia at 37 degrees C: (1) preischemic administration of potassium solution (K(+)-30 mM, Mg(2+)-1.6 mM, osmolarity 330 MOSM/1); ischemia, unmodified reperfusion; (2) preischemic administration of this solution, ischemia, postischemic administration of this solution for 5 minutes (normothermic cardioplegic reperfusion), putting in a working regimen; (3) the regimen of the experiments is the same as in series 2, but normothermic cardioplegic reperfusion was carried out with a modified potassium-magnesium solution (K(+)-15 mM, Mg(2+)-15 mM, osmolarity 360 MOSM/1). The values of functional restoration, rate and total discharge of the enzyme LDH into the perfusate were compared. Restoration of functional values (aortic pressure, aortic output, cardiac index) according to the experimental series: 3 greater than 2 greater than 1. LDH discharge into the perfusate: 3 less than 2 less than 1. The results of the study provide evidence that reperfusion damage may be lessened by normothermic cardioplegic reperfusion; the highest effect was produced by a solution with specially selected properties: electrolyte composition and high osmolarity.