The Susceptibility of Doubly Suprarenalectomized Rabbits to Acetonitril

Abstract

In order to know the effect of the removal of both the suprarenals in rabbits upon their resistance to acetonitril the present investigations were undertaken. Acetonitril (Merck) was given intravenously, the minimum lethal dose was estimated for normal rabbits as 0.55 c. c. per kilo of body weight, and the maximum non-lethal dose, that is the maximum amount of the chemical which does not kill the animal, as 0.25 c. c. per kilo. When both the suprarenals were excised with an interval of one week and acetonitril was given one week after the last decapsulation, the resistance of the animals was reduced remarkably, 0.4 c. c. and 0.05 c. c. being estimated as the minimum lethal dose respectively the maximum non-lethal dose. When two weeks were allowed to elapse between both the decapsulations, with otherwise quite the same conditions related above, the resistance was decidedly greater than the above group, though on the other hand definitely smaller than the normal, the doses being noted as 0.5 c. c. and 0.1 c. c. The resistance of the animals, in which only the dummy operations were carried out with one-week interval and followed by acetonitril also with one-week interval, was further proved greater than the doubly decapsulated in the last mentioned manner. In them the minimum lethal dose was quite the same as in the normal, but the maximum non-lethal dose was a little smaller; the resistance of these animals was thus only a little inferior to the normal. The resistance to acetonitril of the rabbits surviving the double suprarenalectomy about three months or more was proved apparently quite the same as that of normal ones if only the minimum lethal dose be taken into account, but it is not quite the same judging from the maximum non-lethal dose. In these animals the latter was 0.15 c. c. per kilo, thus smaller not only than the normal ones but also than the animals with dummy operations. It may be noted by way of caution that the control experiments were run in parallel simultaneously with the principle. The resistance of rabbits to acetonitril one week after the unilateral suprarenalectomy or two weeks after the double splanchnictomy was detected as about the same as the normal, as far as the present experiments are concerned, but we do not assert this because of the incompleteness of these sets, especially of the latter set, of experiments. Through double suprarenalectomy the susceptibility of rabbits to acetonitril increased without a doubt, but it was of quite a minor grade, compared to the results obtained by Crivellari on rats. Some recovery of the diminished resistance to acetonitril of rabbits deprived of both the glands with lapse of time suggests some possible causal relationship existing between it and the compensatory hypertrophy of the accessory cortical tissue after removal of the main glands. This view suggests further the responsibility of the great reduction in cortical tissue for the diminished resistance to acetonitril of the doubly suprarenalectomized rabbits. For estimating the susceptibility or resistance of animals to some chemicals the determination of the maximum non-lethal dose can not only replace that of the minimum lethal dose, but also sometimes exceeds the latter in accuracy. To formulate again the results more briefly: Removal of both suprarenals elicits in rabbits an increase of the susceptibility to acetonitril, about 1.5 times of the minimum lethal dose of the normal and 5 times of the maximum non-lethal dose being recorded in the animals, deprived of one suprarenal two weeks previously and of the other one week previously. With lapse of time after the removal the susceptibility is apt to recover towards the initial, but three to nine months were proved insufficient to see the entire recovery. The maximum non-lethal dose was still small, though the minimum lethal dose was quite the same as with normal rabbits.