Effects of Humoral Factors Released from Ischemic-preconditioned Hearts on Survival of Pancreatic Cells Exposed to Hypoxia: An In vitro Study Using Neonatal Pigs

ABSTRACT

PURPOSE: Brief myocardial ischemia evokes a cardioprotective response, referred to as "Ischemic Preconditioning", that limits injury caused by a subsequent prolonged ischemic insult. The myocardial ischemic preconditioning effect can be induced by ischemia of "distant" cardiac and noncardiac tissue, implicating the involvement of an as-yet unidentified humoral trigger. The purpose of this study was to prove the protective effect of a preconditioning ischemic trigger (PIT) obtained from coronary effluent to isolated pancreatic cells under hypoxic condition in neonatal pigs. METHODS: Isolated hearts were preconditioned 5 times with 5-min ischemia following 10-min reperfusion. Coronary effluent was collected during reperfusion, filtered by using a Sep-Pak C-18 catridge, and lyophilized after dissolving it with acetonitrile. Isolated pancreatic cells were divided into a PIT-treatment group and a control group, and each group was further divided into time-dependent and dose-dependent groups. Time-dependent groups were incubated under a hypoxic condition for durations of 1, 2, 3, and 4 hrs, and dose-dependent groups were treated with 3 different doses of PIT that had undergone hypoxic incubation for 4 hrs. Viability of the pancreatic cells after the hypoxic incubation period was evaluated by using a confocal microscope. RESULTS: In the control group, the average viability of pancreatic cells after 4 hrs of hypoxia was 60.48 +/- 1.24%, and in the PIT-treated group, the value was 71.88 +/- 1.33%, the difference in the viability between the PIT-treated group and the control group after 4 hrs of hypoxia was statistically significant. In the dose-dependent groups, the viability of pancreatic cells was significantly larger in the groups treated with original PIT and 1/10 PIT than in the control group. CONCLUSION: These data suggest that in the In-vitro pig model, PIT obtained from heart evoked ischemic tolerance to isolated pancreatic cells.