Nifedipine and alpha-adrenoceptor function in human finger skin vessels.

Experiments were designed to study the effect of the calcium entry blocker nifedipine on contractions evoked by alpha-adrenoceptor activation in human finger skin vessels and to show whether nifedipine could prevent the vasoconstriction induced by local cooling. Vasoconstriction of finger skin vessels was evoked with phenylephrine (a preferential alpha 1-adrenoceptor agonist), B-HT933 (a preferential alpha 2-adrenoceptor agonist) and by local cooling. The alpha-adrenoceptor agonists were administered into the skin by iotophoresis and local cooling was produced with a Peltier element. Nifedipine significantly attenuated the vasoconstrictor responses both to alpha 1- and alpha 2-adrenoceptor stimulation, the effect on alpha 2-mediated responses being more pronounced. It had no effect on the vasoconstriction induced by local cooling of finger skin.