Attenuation of glycogenolytic action of activin a in intact rat
liver.
Kojima, Itaru, Romi Nobusawa, You-Qing Zhang, Nobuo Sekine, Tetsuya
Mine, and Hiroshi Shibata.
Department of Cell Biology, Institute for Molecular and Cellular
Regulation, Gunma University, Maebashi 371, Japan, Fourth Department
of Internal Medicine, University of Tokyo School of Medicine, Tokyo
112, Japan
APStracts 2:0127E, 1995.
Activin A stimulates glucose production by causing glycogenolysis in
isolated hepatocytes. To determine the physiological significance of
this effect, we examined the effect of activin A on glucose
production in the perfused liver. Unlike in isolated cells, activin A
did not enhance glucose production nor did it cause radiocalcium
efflux in the perfused liver. There was no effect of activin A in the
liver perfused in the opposite direction. Although activin A did not
promote glucose production, it was recovered from +/-.098763421the
hepatic vein in a bioactive form. When liver perfusion was performed
in partially hepatectomized rats, activin A increased radiocalcium
efflux. In isolated hepatocytes, activin A increased inositol
phosphates and the effect of activin A was attenuated by the plasma
membrane fraction of hepatocytes. The inhibitory effect of the plasma
membrane was abolished by digesting the membrane with trypsin. These
results indicate that the effect of activin A on glucose production
is attenuated in the intact liver and that a protein factor(s) in
plasma membrane may be involved in the inhibition.
Received 22 March 1995; accepted in final form 31 May 1995.
APS Manuscript Number E134-5.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 July 1995.