Inositol-phosphoglycan inhibits calcium oscillations in hepatocytes by reducing calcium entry

Inositol-phosphoglycan (IPG) is a putative mediator of insulin action that has been shown to affect numerous biochemical processes. IPG, prepared from liver membranes, promptly inhibited phenylephrine- or vasopressin-induced [Ca 2+] i oscillations when perfused over Fura-2-dextran injected rat hepat...

Full description

Saved in:
Bibliographic Details
Published in:Cell calcium (Edinburgh) 1997-02, Vol.21 (2), p.125-133
Main Authors: Sanchez-Bueno, Antonio, Greenwood, Mark R., Varela-Nieto, Isabel, Marrero, Isabel, Gil, Beatriz, Mato, Jose M., Cobbold, Peter H.
Format: Article
Language:English
Subjects:
Animals
Calcium - metabolism
Cells, Cultured
Chlorides - pharmacology
Fluorescent Dyes
Fura-2
Inositol Phosphates - pharmacology
Insulin - pharmacology
Insulin Antagonists - pharmacology
Liver - cytology
Liver - metabolism
Male
Manganese - metabolism
Manganese Compounds - pharmacology
Microinjections
Nitrous Acid - pharmacology
Phenylephrine - pharmacology
Polysaccharides - pharmacology
Rats
Rats, Wistar
Vasopressins - pharmacology
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Inositol-phosphoglycan (IPG) is a putative mediator of insulin action that has been shown to affect numerous biochemical processes. IPG, prepared from liver membranes, promptly inhibited phenylephrine- or vasopressin-induced [Ca 2+] i oscillations when perfused over Fura-2-dextran injected rat hepatocytes. An antibody to IPG suppressed the inhibitory effect of insulin on the [Ca 2+] i oscillations. Measurement of the rate of quench of cytoplasmic Fura-2 by extracellular Mn 2+ showed that Ca 2+ entry occurred continuously in the unstimulated cell and was not affected by phenylephrine or vasopressin. IPG, specifically, almost completely abolished the Mn 2+ quench rate. Elevated extracellular [Ca 2+] reversed the inhibitory effect of IPG on [Ca 2+] i oscillations. We conclude that IPG inhibits the hepatocyte Ca 2+ oscillator by reducing the continuous Ca 2+ influx that is required to sustain oscillations in [Ca 2+] i.
ISSN:0143-4160
1532-1991
DOI:10.1016/S0143-4160(97)90036-1