VASCULAR LEAKAGE INDUCED BY HISTAMINE, BRADYKININ, SEROTONIN AND PROSTAGLANDIN-E2 IN GREYHOUNDS

Vascular leakage induced by intradermal injection of histamine, bradykinin and serotonin alone and co-injected with prostaglandin E2 was measured in Greyhounds using Iodine-125-labelled human serum albumin (I-125-HSA) as a marker in the blood. Histamine and bradykinin produced dose-dependent vascular leakage. At equimolar concentrations, histamine was more than twice as potent as bradykinin. Serotonin did not induce vascular leakage and was irritant. Prostaglandin E2 did not induce significant vascular leakage (maximum 5 muL) when injected alone, but when co-injected with histamine and bradykinin, the vascular leakage of both histamine and bradykinin was Increased. This effect was more pronounced if lower concentrations of histamine and bradykinin were injected. The induced vascular leakage was greatest during the first five minutes of lesion development for histamine, during the second five minutes of lesion development for bradykinin, and the synergistic effect of prostaglandin E2 was maximal during the third five minute period of lesion development.