Effect of starvation upon insulin secretion in the rabbit

Summary Plasma insulin and blood glucose levels of normal and fasting rabbits have been studied. The mean plasma insulin of pre-starvation controls was 24 µU/ml; blood glucose was 107 mg/100 ml. After starvation, the insulin levels in the blood decreased to 8 µU/ml and glucose concentration to a mean level of 76 mg/100 ml. The fine structure of - and -cells was studied in fasted animals. Most of the -cells were filled with granules of the pale type and some of these secretory granules were adjacent to the plasmatic membrane, which frequently showed projecting microvilli. Immunoassay figures for pancreatic insulin were obtained. There was a good correlation between the insulin assay results in pancreas on one hand, and light and electron microscopic -cells on the other, provided the assumption is true that pale granules contain immunologically active insulin. Most of the -cells were well granulated, but a few of these cells showed a marked increase in the lamellar ergastoplasm.This work has been supported by a grant from the Seguridad Social del Estado, Madrid.