Actions of some vasodilators on isolated human hand veins

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Abstract
Actions of some vasodilators on isolated human hand veins.Acta Physiol Scand130, 671–677. Received 7 October 1986, accepted 16 March 1987. ISSN 0001–6772. Department of Hand Surgery, Malmö General Hospital, and Department of Clinical Pharmacology, University of Lund, Sweden.Vasospasm is a well recognized complication during micro vascular surgery of the hand. In the search for new spasmolytic drug therapies, the effects of papaverine, nitroprusside, nimodipine and lidocaine on isolated human hand veins contracted by several postulated mediators of vasospasm were examined. Mechanical activity was recorded isometrically in ring segments of the vessels. Potassium ions, noradrenaline (NA), 5‐hydroxytryp‐tamine (5‐HT) and prostaglandin F2α(PGF2α) all produced strong contractions that were highly dependent on the presence of extracellular Caa+. Papaverine acted as a non‐selective vasodilator, as it produced an almost identical inhibition of contractile responses to all examined stimulants. Nitroprusside inhibited contractions induced by agonists more than those evoked by K+, whereas the opposite was found for nimodipine. Nitroprusside also seemed to display a certain degree of selectivity among the agonist‐induced responses (NA > PGFaα> 5‐HT). Lidocaine increased the contractile response to K+and at high concentrations (> 10‐‐5M)produced a contractionper se. The clinical efficacy of lidocaine as a vasodilator after topical application therefore seems to reflect an inhibitory action on vasoconstrictor nerves. Papaverine, nitroprusside, nimodipine and lidocaine differ considerably in their profiles of action and therefore deserve to be further evaluated in the treatment of vasospasm during microvascular surgery.