The relation of the parathyroid glands to the action of irradiated ergosterol

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Abstract
In a previous communication (Taylor, Weld, Branion and Kay, 1931) we drew attention to the similarity between the effects upon dogs of overdosage with parathormone and those induced by excessive doses of irradiated ergosterol. A large number of animals were studied and several different aspects of the overdosage manifestations of the hormone and the vitamin were compared. The rise in the serum calcium effected by large doses of either of these two substances had been sufficient alone to suggest to many investigators some fundamental relationship between their actions. The suggestion was given the colour of reality by the facts, that whichever agent was employed, the magnitude of the calcium rise and the excretory response of the kidney were found to be essentially the same. The urinary calcium is greatly increased and the volume and total acidity of the urine rises in either instance. Other features common to the actions of the two substances are the rise in the non-protein nitrogen of the blood and a great elevation of the blood phosphorus in the terminal stages of the overdosage condition. These resemblances in action we believe are not without significance in view of the fact that no other agent is known to cause a comparable combination of effects. The experiments carried out at Toronto demonstrated two other remarkable points of similarity between the actions of the two agents, namely, the closely comparable degrees of susceptibility to either substance exhibited by various species and the identical nature of the vascular changes in the gastro-intestinal tract of carnivora, whichever substance was employed. Since the publication of our earlier paper the susceptibility to irradiated ergosterol and parathormone has been investigated in two other species—pigs and lions. Eight young pigs, just weaned, were employed. Three were each given 2 cc doses of irradiated ergosterol (10-000 X) by mouth daily. This amounted to 0.06 cc per kilo of body weight. The remaining animals were kept as controls. One of the treated animals died at the end of the fourth week. Bleeding from the nose and difficulty in breathing were present for a day or two preceding death. At autopsy a hæmorrhagic state of the lungs-was found. The second animal died after 5 weeks of treatment. The postmortem examination showed hæmorrhages into the lungs and gastro-intestinal tract. The third animal showed no ill effects. It gained in weight throughout the experiment and in no way appeared different from the controls. From these results the susceptibility of pigs to the overdosage effects appears to be little different from that of dogs. Other members of this species exhibited a corresponding degree of susceptibility to the effects of parathormone.