Alteration of cellular electrophysiologic properties in porcine pulmonary microcirculation after preservation with University of Wisconsin and Euro-Collins solutions

Background The effect of cold storage of porcine pulmonary microvessels in University of Wisconsin (UW) and Euro-Collins (EC) solutions on the cellular electrophysiologic properties remains unknown. Methods The pulmonary microarteries (PA, 381.6 ± 62.8 μm; N = 60) and microveins (PV, 360.8 ± 54.5 μm; N = 60) were incubated with Krebs (control), UW, or EC solution at 4°C for 4 hours in a myograph. The resting membrane potential and the endothelium-derived hyperpolarizing factor–mediated hyperpolarization to bradykinin (0.1 μmol/L) in the presence of inhibitors of nitric oxide and prostacyclin, Nω-nitro-l-arginine, hemoglobin, and indomethacin, in a single smooth muscle cell were directly measured. Results The resting membrane potential (−60.8 ± 1.3 mV in PA and −48.1 ± 0.7 mV in PV, N = 6) was depolarized after exposure to UW solution (to −18.4 ± 0.7 mV in PA and −13.6 ± 0.8 mV in PV; N = 8; p< 0.001). The amplitude of endothelium-derived hyperpolarizing factor–mediated hyperpolarization to bradykinin was also decreased (from 7.4 ± 0.7 mV to 2.6 ± 0.7 mV in PA and from 4.6 ± 0.5 mV to 0.9 ± 0.4 mV in PV; p< 0.001). In comparison, EC depolarized the membrane potential to a lesser extent (to −28.3 ± 0.9 mV in PA and to −21.3 ± 0.8 mV in PV; N = 8; p< 0.001) and almost abolished the hyperpolarization to bradykinin. After washout, hyperpolarization was partially restored (UW, 4.9 ± 0.7 mV in PA and 2.0 ± 0.3 mV in PV. p< 0.01; EC, 2.3 ± 0.5 mV in PA and 1.0 ± 0.3 mV in PV. p< 0.01). Conclusions Cold storage of porcine PA and PV with UW or EC solution impairs the electrophysiologic properties (hyperpolarization) related to endothelium–smooth muscle interaction. The alteration is more profound with EC than UW solution and in veins than in arteries. The findings urge further studies on lung preservation solutions.