Comparison of University of Wisconsin and St. Thomas' Hospital solutions on endothelium-derived hyperpolarizing factor-mediated function in coronary micro-arteries

Background. It is controversial whether coronary endothelial function is impaired after cold exposure to University of Wisconsin (UW) or St. Thomas' Hospital (ST) solution during heart transplantation. We therefore examined the effects of cold storage of coronary micro-arteries with UW or ST solution on endothelium-derived hyperpolarizing factor (EDHF)-mediated function. Methods. Porcine and human coronary arteries were immersed in either UW or ST solution at 4°C for 4 hr and then normalized in a wire myograph. Results. In the rings (normalized diameter: 200-500 μM) precontracted by U(46619), EDHF- mediated relaxation and hyperpolarization were initiated by bradykinin (BK) or A(23187) in the presence of indomethacin and N(G)-nitro-L-arginine. In the human coronary arteries, the EDHF-mediated relaxation to BK was reduced by UW solution from 53.2±5.6% to 24.0±2.7% (P=0.006). The reduced EDHF-mediated relaxation occurred concurrently with the decreased hyperpolarization to BK (17.0±1.5 vs. 10.5±1.1 mV, n=10, P=0004) or A(23187) in porcine coronary arteries. In the control arteries, K⁺ channel blockers, either glybenclamide or tetraethylammonium reduced the EDHF-mediated relaxation. After exposure to UW solution, the EDHF-mediated relaxation was further significantly inhibited. In contrast, ST solution did not affect these responses. Conclusions. These results show that in coronary micro-arteries, UW, but not ST, solution impairs the EDHF-mediated function and inhibits the Ca²⁺ activated and ATP-sensitive K⁺ channels. Our comparative study suggests that ST solution may be superior to UW solution in preserving the EDHF-related endothelial function of coronary micro-arteries.