Donor heart preservation with pinacidil: The role of the mitochondrial K _ATP channel

Background Pinacidil solutions have been shown to have significant cardioprotective effects. Pinacidil activates both sarcolemmal and mitochondrial potassium-adenosine triphosphate (K _ATP) channels. This study was undertaken to compare pinacidil solution with University of Wisconsin (UW) solution and to determine if the protective effect of pinacidil involved mitochondrial or sarcolemmal K _ATP channels. Methods Thirty-two rabbit hearts received one of four preservation solutions in a Langendorff apparatus: (1) UW; (2) a solution containing 0.5 mmol/L pinacidil; (3) pinacidil with Hoechst-Marion-Roussel 1098 (HMR-1098), a sarcolemmal channel blocker; and (4) pinacidil with 5-hydroxydecanote, a mitochondrial channel blocker. Left ventricular pressure-volume curves were generated by an intraventricular balloon. All hearts were placed in cold storage for 8 hours, followed by 60 minutes of reperfusion. Results Postischemic developed pressure was better preserved by pinacidil than by UW. This cardioprotective effect was eliminated by 5-hydroxydecanote and diminished by HMR-1098. Diastolic compliance was better preserved by pinacidil when compared with UW. This protection was abolished by the addition of 5-hydroxydecanote and moderately decreased by HMR-1098. Conclusions Our results support the superiority of pinacidil over UW after 8 hours of storage. The cardioprotective role of pinacidil is mediated primarily by the mitochondrial K _ATP channel.