Abstract
The aim of the present experiments was a determination of the minimal rate of injection of epinephrine which causes a rise in blood sugar of rats. Similar experiments on rabbits could be made without anesthesia but this was unfortunately not possible on rats. Though amytal anesthesia has little effect on the blood sugar of rats, as may be seen in Table I, it undoubtedly lowers the carbohydrate tolerance. Animals in the postabsorptive state with a high liver glycogen content on account of previous carbohydrate feeding were used. 0.1 to 0.2 cc. of blood was withdrawn from a femoral vein by means of a syringe at the beginning and end of the injection. A third sample was taken 30 minutes after the end of the injection. The temperature of the animals was kept between 97.8 and 99° F., heat being supplied by an electric bulb. The dilutions of epinephrine were made with a slightly acidified physiological salt solution and as a control the same salt solution was injected. The injections of epinephrine lasted for 30 minutes. It is concluded from the data of Table I that 0.0002 mg. per kilo per minute is the smallest rate of injection which produces a definite rise in blood sugar of amytalized rats.
The relation between the pressoric and hyperglycemic rate of epinephrine injection in different species, as determined recently in this laboratory, is shown in Table II. This comparison shows that the carbohydrate metabolism and the vascular system of the rat is decidedly less sensitive to epinephrine than that of the other species investigated.
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