Different endothelium-dependent relaxations in arterial and venous coronary bypass grafts - Lüscher, T F; Diederich, D; Siebenmann, R; Lehmann, K; Stulz, P; von Segesser, L; Yang, Z; Turino, M; Grädel, E; Weber, E; Bühler, F R (N Engl J Med, 1988)