5-Hydroxytryptamine, Tissue Mast Cells and Skin Oedema

Abstract

(1) 5-Hydroxytryptamine is not concentrated in tissue mast cells in the guinea pig, dog, man, cow, horse, rabbit, ox, hog, hamster or cat. It may be partly associated with tissue mast cells in the rat and mouse. (2) The skin of the rat contains more than half of the total 5-HT in the body. This can be depleted by treatment with reserpine. On the other hand, the rat can be depleted of its histamine by treatment with polymyxin B. (3) Substances which produce the anaphylactoid reaction in rats (e.g. dextran and eggwhite) release 5-HT as well as histamine from skin tissues. The reaction is prevented by depletion of the skin 5-HT using reserpine but it is not prevented by depletion of skin histamine alone. The reaction is prevented by previous administration of the specific anti-5-HT compound, BOL 148, but it is only slightly modified by antihistamine substances. (4) It is concluded that the anaphylactoid reaction in rats is mediated chiefly through the release of 5-HT.