SPERMINE, ZINC AND INSULIN

¹ Connaught Laboratories, University of Toronto

Freshly prepared samples of spermine and insulin containing a small amount of added zinc showed no greater hypoglycaemic action in rabbits than did similar preparations containing insulin and the added zinc. These results confirm our previous observations and are in marked contrast to those obtained when dogs were used as experimental animals. When suspensions of spermine and insulin were incubated at 52°C. the precipitates adhered firmly to the bottom of the glass vials, whereas similar preparations containing a small amount of added zinc could be readily resuspended after incubation. This is in accord with the results of previous experiments wherein it was observed that the physical stability of mixtures of protamine and insulin was increased by the addition of a small amount of zinc. Suspensions of amorphous insulin, spermine and zinc, when incubated at 52°C. for 5 days, showed sustained insulin action in rabbits. The administration, to rabbits, of suspensions of crystalline insulin and spermine did not cause any greater hypoglycaemia than did similar preparations containing no spermine. The physiological effect of incubated suspensions of spermine, zinc and crystalline insulin was not markedly different from that of freshly prepared samples. The possible significance of the results is discussed.