ATP gated potassium channels in acute myocardial hibernation and reperfusion

Objective: ATP gated potassium (KATP) channels and adenosine are of crucial importance in coronary blood flow regulation and activation of KATP channels and adenosine receptor stimulation protect against infarction and development of stunning. The aim of this study was to test the hypothesis that opening of KATP channels and adenosine receptor stimulation are involved in perfusion-contraction matching, in acute hibernation, and in recovery after reperfusion. Methods: 30 isolated piglet hearts (2-10 d old) and 20 isolated rabbit hearts were studied. The isolated piglet hearts were perfused with modified Krebs Henseleit (KH) solution enriched by washed human red blood cells; the isolated rabbit hearts were perfused with modified KH buffer. The effects of the KATP channel opener aprikalim (1 μM), the KATP channel antagonist glibenclamide (30 μM), and the adenosine receptor antagonist 8-(p-sulphophenyl)theophylline (SPT, 300 μM) on 2 h of low flow (10%) ischaemia and 1 h reperfusion were compared with saline in the piglet hearts. The effects of aprikalim (1 jxM), glibenclamide (30 μM), and saline during 90 min of low flow (10%) ischaemia followed by 1 h reperfusion were also examined in the isolated rabbit hearts. Results: At constant coronary flow aprikalim reduced perfusion pressure from 53(SEM 5) to 25(1) mm Hg (p