HISTAMINE WEAL FORMATION AND ABSORPTION IN MAN

Abstract

The weal and flare response to intradermal histamine was measured over a range of doses in forearm skin of man. The use of calipers to measure weal thickness was validated by measurement of observer and method errors. Repeated measurements at intervals of 5 min or more compressed the weals by 6% per reading. Flare response reached a maximum at 5 min compared with 20 min for weal thickness and the sensitivity of the flare response was greater than the weal response at lower doses of histamine. Sensitivity, λ was comparable for the measurement of flare, weal diameter and thickness or volume. The advantage of weal thickness was in the measurement of weal formation and resorption. The time course of histamine weal formation and disappearance was measured and found to have a T1/2 of 5.4 min and 87 min, respectively. The T1/2 of disappearance of comparable 0.9% w/v NaCl solution and serum weals were 18 and 28 min respectively. It is suggested that persistence of histamine weals is due to a vasoactive agent other than histamine. 1980 British Pharmacological Society