Saphenous vein endothelium-dependent relaxation in patients with peripheral vascular disease

In vitro vasomotor responses of saphenous veins of 15 patients undergoing peripheral vascular bypass procedures were studied. Vessels were harvested by standard techniques, sectioned into 4 mm rings, and suspended in organ baths under isometric tension. Stimulation with cumulative doses of norepinephrine revealed a -logED50 of 6.85 +/- 0.12 M and maximal tension of 8.64 +/- 1.77 g. Patient characteristics suggesting high maximal response (by univariate analysis) included male sex (male 11.69 +/- 2.49 g versus female 5.08 +/- 1.69 g; p = 0.058). Intact and denuded rings were additionally tested for endothelium-dependent relaxation following submaximal norepinephrine precontraction. The vessels relaxed in response to acetylcholine (maximal relaxation 31.1 +/- 10.7% at 1 x 10(-6) M), calcium ionophore A23187 (85.3 +/- 11.8% at 1 x 10(-5) M), and sodium nitroprusside (150.8 +/- 15.2% at 1 x 10(-5) M), but only acetylcholine relaxation was completely endothelium-dependent. Calcium ionophore A23187 relaxation was partially dependent on the endothelium while sodium nitroprusside relaxation was entirely endothelium-independent. Negligible relaxation was observed in response to adenosine diphosphate (ADP) (12.1 +/- 12.8% at 1 x 10(-5) M) while histamine and serotonin caused additional contraction only. We concluded that, in patients undergoing vascular surgical procedures, the saphenous vein (1) demonstrates variable contractile function which appears to be greater in males following spinal anesthesia, and (2) exhibits moderate endothelium-dependent relaxation in response to acetylcholine and calcium ionophore A23187 but not to ADP, histamine, or serotonin.