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Current Molecular Medicine

Editor-in-Chief

ISSN (Print): 1566-5240
ISSN (Online): 1875-5666

Hemichannels in Cerebral Ischemia

Author(s): Panagiotis Bargiotas, Hannah Monyer and Markus Schwaninger

Volume 9, Issue 2, 2009

Page: [186 - 194] Pages: 9

DOI: 10.2174/156652409787581646

Price: $65

Abstract

Hemichannels are transmembrane channels that represent the functional subunits of gap junctions. Each hemichannel is composed of a connexin or pannexin hexamer and, after being transported to the membrane, remains unpaired until it is incorporated in a gap junction. Several studies have already provided evidence that gap junction-mediated intercellular diffusion of ions and small molecules during ischemia represents an important mechanism through which necrotic, apoptotic, or even protective signals are transported between cells. Although initially hemichannels were supposed to be functional only in gap junctions, recent findings indicate that unpaired hemichannels also display a large array of activities that can be modulated under several pathophysiological conditions, including ischemia. Open hemichannels in ischemia dramatically alter the permeability properties of membranes and lead to cell death through ionic dysregulation, loss of metabolites, and changes in intracellular ATP. This review focuses on the properties and possible functions of unpaired connexin and pannexin hemichannels and the implications this has for a variety of events, such as cell death, glutamate release, oxidative stress, cortical spreading depression, that occur during an ischemic insult and may affect its outcome.

Keywords: Cerebral ischemia, stroke, connexin, pannexins, hemichannel, gap junction


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