インスリン分泌機構に関する研究

グルコース投与時の膵β細胞の電子顕微鏡的観察

抄録

Glucose was administered intravenously into the normal rat in order to elucidate the mechanism of insulin secretion from pancretic β-cells. The dose of the glucose was three grams per kilogram of the rats weight and glucose was injected twice namely 0 time and 30 minutes after the first injection.
Pancreatic tissue was obtained from these rats 30 minutes after the second glucose injection. Blood glucose level was also measured. For the light microscopic examination, paraffin embedded sections were stained by the aldehyde-fuchsin method of Gomori. For the electron microscopic examination, the tissue was fixed in buffered O3O₄ and was embedded in epon, sectioned with a glass knife and examined at 75 KV using the HU-11 (B) apparatus.
On the light microscopic examinations, the islet tissue from the rats after the administration of glucose showed the degranulation of β-granules. On electron microscopically, many types of β-granules were observed: as reduction of the core, decrease of electron density and disappearance of the core of the β-granules. However, the emiocytosis of the βgranules was not observed even around the capillary wall. There were pores on the unit membrane of the granules.
These findings suggest that the secretion of the insulin from the β-cells of the pancreas is performed by diacrine system but not by emiocytosis.