1. Physiological elevation of plasma vasopressin in man results in a small reduction in skeletal muscle blood flow but the action on skin blood flow has not been reported.
2. We have studied eight male subjects during infusion of arginine vasopressin (AVP) at 2 units/h for 90 min. Plasma levels of AVP, measured by radioimmunoassay, rose to 68.5 (7.0) pg/ml, mean (sem). Forearm and finger blood flow was measured with an electronic plethysmograph, hand interdigital skin-fold blood flow with a laser-Doppler blood flow meter and facial temperature with a thermocouple.
3. All subjects developed marked facial pallor during infusion of AVP, facial temperature falling from 34.2 (0.2) to 32.7 (0.1)°C (P < 0.001) then rising to 33.7 (0.1)°C (P < 0.01) after AVP was stopped. Hand interdigital skin-fold blood flow also fell from 2.6 (0.02) to 2.3 (0.02) V (P < 0.001) and rose sharply to 3.6 (0.2) V (P < 0.001) on stopping the infusion. There were small changes in forearm and finger blood flow: both rose, from 6.3 (0.1) to 6.9 (0.1) (P < 0.001) and 46.1 (1.0) to 54.3 (0.7) ml min−1 100 ml−1 (P < 0.001) respectively. Neither fell when AVP was stopped. Heart rate remained unchanged throughout.
4. These results indicate that high physiological levels of AVP, comparable with those attained during physical stress, produced a fall in blood flow in the face and interdigital skin-fold of the hand consistent with a fall in nutritional blood flow to skin. Blood flow to skeletal muscle, however, remained little changed whereas that through arteriovenous anastomoses in skin of the finger rose.
5. We conclude that AVP has a selective vasoactive effect in skin, constricting nutritional blood vessels and venules while promoting an increase in arteriovenous shunting of blood.