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O2 availability modulates transmembrane Ca2+ flux via second-messenger pathways in anoxia-tolerant hepatocytes

Land, S.C., Sanger, R.H. and Smith, P.J. (1997) O2 availability modulates transmembrane Ca2+ flux via second-messenger pathways in anoxia-tolerant hepatocytes Journal of Applied Physiology, 82, (3), pp. 776-783. (PMID:9074963).

Record type: Article

Abstract

Transmembrane Ca(2+)-flux was studied from single isolated turtle hepatocytes by using a noninvasive Ca(2+)-selective self-referencing microelectrode. Cells in Ca(2+)-reduced culture medium demonstrated a vanadate- and lanthanum-inhibitable Ca(2+)-efflux of 4 x 10(-17) mol Ca2+. microns-2. s-1 continuously over 170 h. This flux diminished with 50 nM phorbol 12-myristate 13-acetate, a protein kinase C (PKC) activator, and was reinstated on PKC deactivation with sphingosine. Progressive hypoxia resulted in a reversible suppression of Ca2+ efflux to 90% of normoxic controls with an apparent Michaelis constant for oxygen of 145 microM. PKC activation was critical in this suppression, as anaerobic administration of sphingosine caused a Ca2+ influx and cell rupture. Hypoxia was also associated with an altered pattern of adenosine-mediated control over Ca2+ efflux. Adenosine (100 microM) elevated Ca2+ efflux twofold in normoxia, but neither adenosine nor the A1-purinoreceptor antagonist 8-phenyltheophylline altered the observed anaerobic suppression. Aerobic administration of 2-10 mM KCN failed to reproduce the anaerobic suppression; however, in conjunction with 10 mM iodoacetate, complete metabolic blockade caused a Ca2+ influx and cell rupture. These observations suggest modulatory control by oxygen over transmembrane Ca2+ efflux involving second-messenger systems in the hypoxic transition.

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Published date: March 1997
Keywords: oxygen sensing, hypometabolism, adenosine, protein kinase c, calcium homeostasis, calcium-selective self-referencing probe

Identifiers

Local EPrints ID: 190249
URI: http://eprints.soton.ac.uk/id/eprint/190249
ISSN: 8750-7587
PURE UUID: 146fb80d-e01d-4b8a-b62e-b0f69a8fc427
ORCID for P.J. Smith: ORCID iD orcid.org/0000-0003-4400-6853

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Date deposited: 17 Jun 2011 10:24
Last modified: 18 Jul 2017 11:39

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Contributors

Author: S.C. Land
Author: R.H. Sanger
Author: P.J. Smith ORCID iD

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