Abstract
In a previous communication 1 the protective action of injections of cortin on the resistance of suprarenalectomized rats to typhoid vaccine was reported. In these studies an extract of the cortex of the suprarenal gland, made in this laboratory according to the method of F. A. Hartman, was used. It was found that Hartman's cortin is a highly potent extract of the suprarenal cortex. It is free of toxicity and epinephrin. Repeated injections of cortin will raise the resistance of suprarenalectomized rats to several lethal doses of typhoid vaccine. It was suggested that a cortical extract may be biologically assayed by determining the minimal protecting amount to be administered within 24 hours before and after the injection of the minimal lethal dose of typhoid vaccine for suprarenalectomized adult rats on the 6th day after suprarenalectomy.
In the following experiments the effect of injections of cortin on the resistance of suprarenalectomized rats to histamine (ergamine acid phosphate, Burroughs Wellcome) was studied. Previous work 2 had shown that suprarenalectomized rats are highly susceptible to histamine poisoning. It was suggested that histamine could be used as a gauge of suprarenal insufficiency. Adult suprarenalectomized rats are killed by 100-120 mg. of histamine per kg. when administered on the 6th day after operation. 2 , 3 Normal rats survive 700-900 mg. per kg. 4 , 5 , 2
Preliminary tests in the present studies indicated that immature suprarenalectomized rats will resist larger amounts of histamine than mature suprarenalectomized rats. Six-week-old immature albino rats of Wistar stock were used. The minimal lethal dose of histamine for 6-week-old suprarenalectomized rats was determined. Twenty-four suprarenalectomized, 6-week-old albino rats were divided into 3 groups. Five received on the 6th day after operation 100 mg. per kg. of body weight of histamine, 14 received 150 mg. per kg. and 5 received 200 mg. per kg.
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