Abstract
In the course of an investigation concerning the interaction of the calorigenic actions of 2–4 dinitrophenol and epinephrine, we have observed a marked sex difference in the susceptibility to dinitrophenol intoxication, as judged by the survival time to a dose which was, under our experimental conditions, almost invariably fatal. There do not appear to have been any reports in the literature concerning sex-differences in the action of dinitrophenol.
Adult cats, previously starved for 24 hours, were anesthetized with pentobarbital (37.5 mg. per kilo intraperitoneally), and attached to a closed circuit metabolism apparatus by means of a tracheal cannula. After a preliminary control period of one-half hour, a quantity of sodium 2–4 dinitrophenolate adequate to yield 10 mg. per kilo of dinitrophenol was injected intramuscularly. In certain experiments, an epinephrine solution was infused intravenously at a rate of 0.001 mg. per kilo per minute during the period of dinitrophenol action. (The Ringer's solution used contained 1 part of defibrinated blood to 10 parts of saline to protect the epinephrine against oxidation. 1 ) In the remaining experiments Ringer's solution was infused at the same rate. Oxygen consumption, rectal temperature, and respiratory rate were followed.
In the table, the survival times of the animals are given in minutes after the injection of dinitrophenol. Among the cats receiving dinitrophenol alone, the males survived on the average 226 minutes, the females 61 minutes. The reliability of this difference was calculated by the variance method of Fisher. 2 The odds that this difference could have appeared by chance were less than 1 in 5000. Thus, even though the number of cases is small, the reliability of the difference is established beyond reasonable doubt.
Among the cats given epinephrine as well as dinitrophenol, a similar difference appeared, the male survival time averaging 117 minutes, the female 34 minutes.
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