ENDOTHELIUM-DERIVED RELAXING FACTOR RELEASE FROM NORMAL AND VARICOSE HUMAN SAPHENOUS VEINS

Objective: To evaluate the role of endothelium-derived relaxing factor (EDRF) in the regulation of smooth muscle tone in normal and varicose human saphenous veins. Design: An in vitro study of site-matched saph enous vein samples from patients undergoing varicose vein surgery or c arotid endarterectomy. Setting: Department of Surgery, University of L eicester, Leicester Royal Infirmary. Patients: Nine patients undergoin g varicose vein surgery and seven patients undergoing carotid endarter ectomy. Measurements: Vein samples were contracted with noradrenaline and relaxation studies performed with acetylcholine (endothelium-depen dent) and sodium nitroprusside (endothelium-independent). Results: The re was no statistical difference in either smooth muscle contraction i n response to noradrenaline or in endothelial-dependent relaxation in response to acetylcholine. All veins retained the ability to relax in response to nitroprusside. Conclusions: No evidence of a defect in eit her smooth muscle function or EDRF release has been found that may con tribute to the aetiology of varicose veins.