The Effect of Histamine on the Human Fingertip Circulation

Publisher Website
Google Scholar
Abstract
The effect of intraarterial histamine on fingertip blood flow (FBF) and vascular resistance (FVR) was studied in normal subjects during reflex sympathetic vasoconstriction induced by body cooling and vasoconstriction caused by intraarterial noradrenaline [norepinephrine]. In a room at 20.degree. C, FBF increased from 15.3 .+-. 35.5 (SD) to 28.3 .+-. 55.9 ml min-1 100 ml-1 of tissue and FVR decreased from 23.7 .+-. 17.7 to 11.9 .+-. 9.9 mm Hg .cntdot. ml min-1 100 ml-1 (P < 0.01) during infusions of histamine (0.5-4 .mu.g/min) in 14 subjects. In 9 of these subjects, the disappearance half times of local injections of Na131I were measured and decreased from 19.8 .+-. 10.9 to 12.9 .+-. 7.3 min during histamine infusions, indicating an increase in nutritional flow. Arteriovenous shunt flow was also probably affected for increases in FBF were sometimes large and FBF increased without a change in the radioisotope half time in 2 subjects. Neither cimetidine nor pyrilamine (mepyramine) consistently prevented the FBF responses to histamine. Administration of both antihistamines together attenuated the response. During noradrenaline infusions in 4 subjects, a large increase in FBF (8.9 .+-. 10.9 to 39.0 .+-. 8.2 ml, P < 0.005) occurred at the smallest dose (0.5 .mu.g/min) of histamine. Histamine can vasodilate fingertips and increase nutritional blood flow during reflex sympathetic vasoconstriction. This vasodilatation may be mediated via both histamine H1 and H2 receptors.