Premium
An electron microscopic and biochemical study of the effects of glucagon on glycogen autophagy in the liver and heart of newborn rats
Author(s) -
Kondomerkos D.J.,
Kalamidas S.A.,
Kotoulas O.B.
Publication year - 2004
Publication title -
microscopy research and technique
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.536
H-Index - 118
eISSN - 1097-0029
pISSN - 1059-910X
DOI - 10.1002/jemt.20000
Subject(s) - glycogen , glucagon , medicine , endocrinology , maltose , glycogenesis , glycogenolysis , chemistry , glycogen branching enzyme , biology , biochemistry , glycogen synthase , enzyme , insulin
The effects of glucagon on the ultrastructural appearance and acid glucosidase activities in the liver and heart of newborn rats were studied. Liver or heart glycogen‐hydrolyzing activity of acid glucosidase increased 3 hours after birth and gradually decreased from 3 to 9 hours. Maltose‐hydrolyzing activity of acid glucosidase also rose 3 hours after birth, maintained a plateau between 3 and 6 hours, and fell at 9 hours. The administration of glucagon increased autophagic activity in the hepatocytes at the age of 6 hours. Glycogen inside the autophagic vacuoles was decreased, apparently due to the increased glycogen degradation. Glycogen‐hydrolyzing activity was elevated in both the liver and the heart. Maltose‐hydrolyzing activity was elevated in the liver, but not in the heart. The results of this study suggest that the glycogen‐hydrolyzing and maltose‐hydrolyzing activities of acid glucosidase are due to different enzymes. Glucagon's effect on the glycogen‐hydrolyzing acid glucosidase activity and autophagosomal morphology is similar in both the liver and the heart. Microsc. Res. Tech. 63:87–93, 2004. © 2004 Wiley‐Liss, Inc.