Background: This study investigates the efficacy of pinacidil, an adenosine triphosphate-sensitive potassium (KATP) channel opening agent, added to custadiol solution on myocardial protection during deep hypothermia and prolonged global ischemia on isolated rat hearts.
Methods: After 20 minutes of stabilization, 24 rats were divided into two groups. In group I (n=12), hearts were arrested with cold (4 degrees C) custadiol solution containing 50 micromol/L of pinacidil and subsequently dipped into the same solution for 120 minutes at 4 degrees C. Group I hearts were perfused with low-flow pinacidil-custadiol (PC) solution during the ischemic period. Group II (n=12) hearts, after the stabilization period, were arrested with cold custadiol solution only, then subsequently dipped and perfused with the same solution for 120 minutes at 4 degrees C. All hearts were reperfused with Krebb's-Henseleit solution at 37 degrees C for 60 minutes. Hemodynamic parameters (peak systolic pressure, end diastolic pressure, maximum rate of increase of left ventricular pressure [+dP/dt], ischemic contracture, and coronary sinus flow) were recorded at the end of the stabilization period and at 10-minute intervals during the reperfusion period. Biochemical data (creatine kinase [CK-MB] washout and troponin I [cTnI] levels) were compared between the two groups.
Results: There was no significant difference in any hemodynamic or biochemical parameters between the two groups during the stabilization period. The peak systolic pressure, +dP/dt, ischemic contraction amplitude, and coronary flow values were significantly higher in group I ( P<0.05) compared with group II during reperfusion. End diastolic pressures as well as CK-MB and cTnI levels were lower in the pinacidil-treated group, which is consistent with improved functional recovery during the reperfusion period.
Conclusion: The addition of pinacidil to the preservation solution, custadiol, improves myocardial recovery after deep hypothermia and prolongs ischemia.