Calcium channel blocker enhances lung preservation.

BACKGROUND: The standard program for lung transplantation employs PGE1 pretreatment for donor lungs, but its efficacy remains controversial. Calcium channel blocker has been reported more effective for reducing potassium-induced vasoconstriction. We investigate the efficacy of calcium channel blocker in the initial lung flush using rat lung transplant model. METHODS: The excised rat lungs (n = 30) were flushed with either University of Wisconsin solution (UWS) with a prior injection of 50 microg/kg PGE1 into the pulmonary artery (UWS + PGE1; n = 7), UWS only (UWS; n = 7), or UWS containing 10(-6) M nifedipine (UWS + Nif; n = 8). After storage (4 degrees C) for 24 hours, all lungs were reperfused for 2 hours using an isolated, pulsatile blood perfused lung model. Control lungs (n = 8) were reperfused immediately after harvest. Blood gas analysis and shunt fraction, lung airway resistance, dynamic lung compliance, and pulmonary vascular resistance were assessed. RESULTS: The pO2 at 30 minutes after reperfusion in the control, UWS, UWS + PGE1, and UWS + Nif group were 88.0 +/- 3.2, 49.6 +/- 2.2, 52.0 +/- 2.4, 85.1 +/- 2.1 (mmHg), respectively. Until 30 minutes after reperfusion, the pO2 in UWS and UWS + PGE1 group were significantly lower than those in UWS + Nif group (p < .001). Shunt fraction, lung airway resistance, and dynamic lung compliance also demonstrated the superiority of UWS + Nif group. CONCLUSIONS: The early graft function after storage was significantly enhanced in lungs flushed with UWS containing nifedipine. Calcium channel blocker is more effective than PGE1 in reducing the potassium-induced vasoconstriction. Optimal composition of the flush may require both calcium channel blocker for pulmonary vasodilation and PGE1 for pulmonary protection by non-vasodilatory mechanisms.