Evaluation of reperfusion strategy for the globally ischaemic rat heart. Recovery of function and energy metabolism

Abstract

Objective: The sequelae of myocardial ischaemia can in principle be alleviated by repeated reperfusion, but the accumulation of adenosine monophosphate (AMP) and the loss of interstitial adenosine may lead to adenylate depletion. Repeated oxidative stress could predispose the heart to reperfusion injury. The aim of this study was to investigate the effect of intermittent reperfusion on myocardial energetics and postischaemic function.

Methods: Isolated retrogradely perfused rat hearts were subjected to 20 min ischaemia, this being continuous in group I while the hearts in group II were reperfused for three 2 min periods at 5 min intervals. Function and energy metabolism were evaluated during the postischaemic reperfusion.

Results: Considerable efflux of adenosine compounds was seen during the final reperfusion, this being greater in group I than in group II, at 6.6(SEM 0.9) v 2.0(0.4) mumol.g-1 dry weight (p < 0.01). Tissue AMP, inorganic phosphate, and adenosine catabolites were higher in group I than in II after the ischaemic insult (p < 0.02), and ATP was higher in group II at the end of the final reperfusion (p < 0.05). All the hearts recovered; however, in group I the rate-pressure product was lower than in group II.

Conclusions: Repetitive reperfusion, although short in duration, is beneficial in ischaemia in terms of lower adenylate loss and better postischaemic recovery. This should be taken into consideration when designing clinical reperfusion interventions.