EFFECT OF HISTAMINE UPON CAPILLARY PERMEABILITY IN THE SKIN AND MUSCLE OF NORMAL AND ADRENALECTOMIZED RATS¹

Abstract

IT is WELL KNOWN that the resistance of the rat and other species to fatal histamine shock is markedly reduced by adrenalectomy (1, 2), and that treatment with adrenal cortical hormone will restore,this resistance to normal (3). The possibility arises that the sensitivity of the adrenalectomised rat is due to an enhanced action of histamine in increasing capillary permeability. This situation would result if either the threshold of capillary sensitivity to histamine or the rate of histamine inactivation is decreased following adrenalectomy. To obtain information on this point, studies were undertaken to determine a) the minimal concentration of histamine which would increase capillary permeability and b) the duration of activity of histamine on capillary permeability in the skin and muscle of normal and adrenalectomiz;ed rats. Changes in capillary permeability2 induced by histamine were evaluated by comparing the amounts of trypan blue accumulated in histamine-treated areas of skin with those in control areas.