STUDIES ON SUPRARENAL INSUFFICIENCY

Abstract

Increased susceptibility to histamine in suprarenalectomized rats follows immediately the removal of the influence of the suprarenal medulla from the circulation. Direct microscopic observation of intestinal or ear blood vessels showed only dilator responses to histamine, applied directly or intravenously. Arteries, veins and capillaries dilated in the order given. The blood pressures of suprarenalectomized rats having transplanted or gross accessory cortical tissue but no demonstrable chromaffin tissue, were similar to those of normal rats. The blood pressures of suprarenalectomized rats having no cortical tissue were distinctly lower, indicating that the low pressure seen in suprarenal insufficiency is concurrent with cortical rather than with medullary defect. The minimal dose of histamine necessary to produce a permanent fall of blood pressure is 0.3-0.5 mgm. per 100 gm. body weight for normal and blank operated rats, and 0.05-0.1 mgm. per 100 gm. for suprarenalectomized rats with or without transplanted or gross accessory cortical tissue. Subcutaneous injections of adrenalin, twice daily during 7 days following supra-renalectomy, did not materially affect the vascular responses to histamine. It is believed that the influence of the suprarenal medulla in protecting the rat from the fatal effects of histamine poisoning is effective by virtue of the physiological antagonism between secreted adrenin and histamine, rather than that the protective action of adrenin is dependent on a continuous effect maintaining the nutrition or tone of some part of the vascular neuro-muscular mechanism.