Induction of Tetany in Rachitic Rats by Means of a Normal Diet.

Abstract

In the study of experimental tetany, removal of the parathyroid glands has generally been resorted to. Following this procedure the calcium concentration of the blood promptly falls and the animal develops tremor or convulsions. Dogs have commonly been used and the thyroid as well as the parathyroids have been extirpated. It is evident that, from a pathogenetic standpoint, this procedure can not be compared with the mechanism of infantile tetany. Another method is to induce tetany by giving large amounts of the phosphates. This procedure likewise can not be considered satisfactory, as it does not reproduce or simulate conditions associated with the development of tetany in human beings. Since infantile tetany comes about almost invariably as a sequel to rickets, it is remarkable that investigators have not more often attempted to induce tetany as a complication of a previously existing rickets. Shohl 1 has clearly recognized the importance of bringing about tetany in rachitic animals and has reported a number of investigations in which this disorder was occasioned by giving phosphates to rachitic rats. More recently Hamilton 2 and his coworkers have induced tetany in rabbits which previously had been rendered rachitic.

Our object was to ascertain whether tetany could be induced in a rachitic animal by means of a ration which more nearly approached the dietary of the infant. The first step was to bring about rickets in young rats in the usual way by feeding them a high calcium, low phosphorus diet. The McCollum ration was used, which has a Ca:P ratio of about 4:1. This ration was fed for about 21 days with the induction of typical rickets. For the development of tetany the Sherman B normal diet was used.