Abstract
There are two views as to the nature of the toxic action of Vitamin D. 1 One is that toxication is a function of the antirachitic unitage, while the other holds that this result depends either on toxic by-products of activation or on end products of metabolism of the vitamin in the body.
In the course of some studies on the alleged hypertensive action of Vitamin D in rats 2 it appeared that different preparations of the vitamin gave different degrees of toxication. Consequently, 3 groups of rats were selected from our standardized stock colony at ages ranging from 245 to 601 days. One of 3 preparations of Vitamin D Was administered to each group in daily doses of 75 units per g of body weight.
Figure 1.
Group 1, comprising 4 males and 5 females received Vitamin D3 (activated 7 dehydrocholesterol in sesame oil),∗ by stomach tube.
Group 2, six males and 6 females received Vitamin D2 † (calciferol in ocorn oil) by stomach tube.
Group, 3, seven males and 4 females, received Vitamin De in the form of ertron, and electrically activated ergosterol.‡ This material was not purified, but the activated stock mix dissolved in corn oil and given by stomach tube.
It is emphasized again that the dose of each preparation was 75 international antirachitic units per g of body weight. There was no standardization of toxic factors, it such exit.
The duration of life in each group is shown graphically in Fig. 1, each unit space representing one rat and each fall, therefore, represents the death of one animal.
In Group 1, the firs rat was found dead on the 11th day, and the 8th on the 26th day: the 9the rat survived to the 67th day. This last survivor was a male, but ordinarily no distinction could be made between the two sexes in survival time. The average period of survival was 29.5 days and 15.4 days respectively.
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