Variations in the Serum-calcium of Rabbits

Abstract

With the object of discovering whether the rise in serum Ca following insulin injections, as described by Davis, Dickens and Dodds, was caused by the insulin itself or by some impurity associated with it the effect of samples of varying degrees of purity was studied. In most experiments 6 rabbits were given insulin and 4 controls received none. No rise in serum Ca was obtained within a short period of time with samples of which the potency varied from 0.05 mg. to 8.0 mg. to the unit. The complete curves for 24 hrs. with 4-hourly injections of small doses of insulin (0.5 unit per kg.) were then followed, both when the rabbits were fed with oats and hay alone and when they received cabbage also. An increase in the serum Ca occurred in both insulin-treated animals and controls only on feeding with cabbage. Cabbage may cause a rise in serum Ca, the effect depending on its previous level, in which seasonal variations play a part. There is no relationship between insulin convulsions and serum Ca. Serum Ca determinations were made by the method of Kramer & Tisdall modified by Clark and Collip.