MORPHOLOGICAL AND BIOCHEMICAL OBSERVATIONS ON CATECHOLAMINE-STORING VESICLES OF RAT ADRENOMEDULLARY CELLS DURING INSULIN-INDUCED HYPOGLYCEMIA

The purpose of this study is to demonstrate a structure – function relationship between the release of catecholamines and the depletion of catecholamine‐storing vesicles from cells of the adrenal medulla. The approach taken here is a comparative study of storage vesicle morphology and population, as determined electron microscopically, and of catecholamine concentration, as determined fluorometrically, in adrenomedullary cells at various times during the extrusion phase of the secretory process. To achieve an increased rate of catecholamine release from the gland, animals were made hypoglycemic by the administration of insulin. At one‐hour intervals following this injection and just prior to sacrifice, the severity of the imposed hypoglycemic state was determined from analysis of the blood serum glucose level. The fine structure alterations in adrenomedullary cells of one gland were then compared with the change in catecholamine content of the contralateral gland. The decline in blood serum glucose following insulin administration resulted in a decrease in both the adrenaline‐stroing vesicle population and adrenaline content of the gland. Copyright © 1969 Wiley‐Liss, Inc.