Diabetes and reactivity of isolated human saphenous vein

Summary. Helical strips of saphenous veins from diabetic (n=8) and non‐diabetic (n= 18) humans were studied in vivo for their responsiveness to several vasoactive agents. Following application of passive force (˜20·0 mN), venous strips from non‐diabetic humans often developed spontaneous phasic contractile activity (12 out of 18 patients; 2–5 contractions/min). These intrinsic changes in force were seen in venous strips from only one diabetic patient. The phasic contractions were not altered by treatment with phentolamine, whereas the calcium channel blocker, D‐600, and calcium‐free solution (1·0 mM EGTA) inhibited the phasic contractions. Saphenous veins from diabetic patients developed less maximal, active tension in response to norepinephrine than those from non‐diabetic patients. Contractile responses to serotonin, angiotensin II, and elevated potassium concentration in saphenous veins from diabetic patients were not different from those in veins from non‐diabetic patients. These observations demonstrate attenuated development of active tension in response to alpha‐adrenergic receptor activation and reduced spontaneous contractile activity in venous smooth muscle from diabetic patients.