Normal endothelial function and decreased vasoreactivity of experimental arterial grafts

During autogenous vascular grafting endothelial cell damage inevitably occurs. In this study we examined the functional and morphologic integrity of experimental arterial grafts. The right external iliac artery was grafted into the right carotid artery of 12 male New Zealand white rabbits. The left external iliac artery was used as the control artery. Four weeks after surgery, isometric tension studies were performed on rings of control artery and arterial graft. Control arteries and arterial grafts precontracted with norepinephrine demonstrated endothelium-dependent relaxation of 28.3% +/- 5.6% and 16.1% +/- 1.7%, respectively, in response to acetylcholine (5 x 10(-6) mol/L). Both control arteries and arterial grafts contracted in response to norepinephrine, histamine, and serotonin. The median effective dose (ED50) of norepinephrine was 4.1 +/- 1.3 x 10(-7) mol/L for control arteries and 62.1 +/- 17.9 x 10(-7) mol/L for arterial grafts (p less than 0.005). Similarly, arterial grafts were less sensitive to histamine; the ED50 of histamine for control arteries was 4.6 +/- 1.3 x 10(-7) mol/L and 51.4 +/- 13.0 x -7 mol/L for arterial grafts (p less than 0.005). In contrast, reactivity to serotonin was unaltered. The ED50 was 4.1 +/- 1.3 x 10(-7) mol/L for control arteries and 4.5 +/- 1.3 x 10(-7) mol/L for arterial grafts. Scanning and transmission electron microscopy revealed a largely intact endothelial surface. These data are markedly different from our previous findings with vein grafts in which serotonin supersensitivity was associated with an absence of endothelium-mediated relaxation to acetylcholine.(ABSTRACT TRUNCATED AT 250 WORDS)