Abstract

It has been shown that the subcutaneous injection into dogs of mixtures produced by the addition of spermine to insulin solutions containing zinc causes a more prolonged hypoglycaemia than that observed following the injection of similar samples to which no spermine had been added. The presence of zinc was also essential for this sustained insulin action. A method is described for the preparation of a substance from beef thymus glands which will prolong insulin hypoglycaemia in rabbits and dogs. As with spermine, zinc is necessary. With respect to their ability to cause hypoglycaemia, suspensions of insulin containing little or no potency in solution (and therefore similar to spermine-insulin-zinc and thymus-insulin-zinc preparations) were not materially different from solutions of the same insulin.