Pharmacological assessment of adrenergic receptors in human varicose veins

Background. Experiments were to characterize pharmacologically adrenergic r eceptors in human varicose veins to the natural transmitter norepinephrine and to an extract of Ruscus. Methods. Greater saphenous veins and Varicose tributaries from patients und ergoing elective surgery for primary varicose disease and portions of great er saphenous veins from patients undergoing peripheral arterial reconstruct ion (control) were suspended for the measurement of isometric force in orga n chambers. Concentration response curves were obtained to norepinephrine o r the extract of Ruscus aculeatus in the absence and presence of selective antagonists of alpha, and alpha(2) adrenergic receptors. Results. Norepinephrine and Ruscus extract caused concentration-dependent c ontractions in all veins. Contractions to norepinephrine were greater in co ntrol veins than in varicose tributaries. Contractions to the extract were greater in varicose tributaries than in greater saphenous veins from varico se patients. Contractions to norepinephrine were reduced similarly by alpha (1) and alpha(2)-adrenergic agonists in control and varicose Veins but to a greater extent by alpha(2)-blockade in greater saphenous veins from varico se patients. Contractions to Ruscus extract were not reduced by alpha-adren ergic blockade in control Veins but were reduced by alpha(2)-adrenergic blo ckade in varicose veins. Conclusions. These results suggest a differential distribution of alpha adr energic receptors on greater saphenous veins from non-varicose patients com pared to those with primary varicose disease. Venotropic agents from plant extract probably exert effects by way of multiple receptor and non-receptor mediated events.