Calcium channel blocker enhances lung preservation

Abstract

Background The standard program for lung transplantation employs PGE 1 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 μg/kg PGE 1 into the pulmonary artery (UWS + PGE 1; n = 7), UWS only (UWS; n = 7), or UWS containing 10 −6 M nifedipine (UWS + Nif; n = 8). After storage (4° 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 pO 2 at 30 minutes after reperfusion in the control, UWS, UWS + PGE 1, 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 pO 2 in UWS and UWS + PGE 1 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 PGE 1 in reducing the potassium-induced vasoconstriction. Optimal composition of the flush may require both calcium channel blocker for pulmonary vasodilation and PGE 1 for pulmonary protection by non-vasodilatory mechanisms.