Extracellular sodium and potassium levels modulate cardiac conduction in mice heterozygous null for the Connexin43 gene

Pflügers Archiv : European journal of physiology
Sharon A GeorgeSteven Poelzing

Abstract

Several studies have disagreed on measurements of cardiac conduction velocity (CV) in mice with a heterozygous knockout of the connexin gene Gja1--a mutation that reduces the gap junction (GJ) protein, Connexin43 (Cx43), by 50 %. We noted that perfusate ionic composition varied between studies and hypothesized that extracellular ionic concentration modulates CV dependence on GJs. CV was measured by optically mapping wild-type (WT) and heterozygous null (HZ) hearts serially perfused with solutions previously associated with no change (Solution 1) or CV slowing (Solution 2). In WT hearts, CV was similar for Solutions 1 and 2. However, consistent with the hypothesis, Solution 2 in HZ hearts slowed transverse CV (CVT) relative to Solution 1. Previously, we showed CV slowing in a manner consistent with ephaptic conduction correlated with increased perinexal inter-membrane width (W P) at GJ edges. Thus, W P was measured following perfusion with systematically adjusted [Na(+)]o and [K(+)]o in Solutions 1 and 2. A wider W P was associated with reduced CVT in WT and HZ hearts, with the greatest effect in HZ hearts. Increasing [Na(+)]o increased CVT only in HZ hearts. Increasing [K(+)]o slowed CVT in both WT and HZ hearts with large W P ...Continue Reading

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Citations

Apr 7, 2017·IJC Heart & Vasculature·Gary TseBryan P Yan
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Mar 6, 2016·American Journal of Physiology. Heart and Circulatory Physiology·Sharon A GeorgeSteven Poelzing
Aug 12, 2016·Pflügers Archiv : European journal of physiology·Rengasayee VeeraraghavanSteven Poelzing
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Oct 9, 2021·American Journal of Physiology. Heart and Circulatory Physiology·Xiaobo WuSteven Poelzing

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