Abstract
In previous experiments it was demonstrated that repeated injections of cortin raise the resistance of suprarenalectomized rats to typhoid vaccine. 1 Similar results were obtained by Hartman and Scott. 2 In subsequent experiments we found that repeated daily injections of cortin raise the resistance of suprarenalectomized rats to 4 and 5 lethal doses of histamine (about 500 mg. of histamine per kg. of body weight). 3 In the following experiments an effort was made to increase further the resistance of suprarenalectomized rats to very large amounts of histamine, by injections of cortin. It has been demonstrated that adult suprarenalectomized rats are killed by 100 to 120 mg. of histamine per kg. when the drug is administered on the sixth day after suprarenalectomy; 4 that immature suprarenalectomized rats are killed by 150 to 200 mg. of histamine 3 ; that normal rats are killed by 700 to 900 mg. of histamine per kg. of body weight. 4 , 5 , 6 In spite of the fact that rats have accessory cortical tissue, it has been the experience in this laboratory that all rats are highly susceptible to the effects of small amounts of histamine injected after removal of the suprarenals, and that if the histamine is administered from the 6th to the 14th day, 100% of rats will succumb to less than 200 mg. of histamine per kg. of body weight. In these experiments the cortical extract used was made in the laboratory according to the method of F. A. Hartman. Cortin is a potent extract of the suprarenal cortex. It is free from toxicity and epinephrin.
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