Attenuating loss of cardiac conduction during no-flow ischemia through changes in perfusate sodium and calcium.

American Journal of Physiology. Heart and Circulatory Physiology
Gregory HoekerSteven Poelzing

Abstract

Myocardial ischemia leads to conduction slowing, cell-to-cell uncoupling, and arrhythmias. We previously demonstrated that varying perfusate sodium (Na+) and calcium (Ca2+) attenuates conduction slowing and arrhythmias during simulated ischemia with continuous perfusion. Cardioprotection was selectively associated with widening of the perinexus, a gap junction adjacent nanodomain important to ephaptic coupling. It is unknown whether perfusate composition affects the perinexus or ischemic conduction during nonsimulated ischemia, when coronary flow is reduced or halted. We hypothesized that altering preischemic perfusate composition could facilitate perinexal expansion and attenuate conduction slowing during global ischemia. To test this hypothesis, ex vivo guinea pig hearts (n = 49) were Langendorff perfused with 145 or 153 mM Na+ and 1.25 or 2.0 mM Ca2+ and optically mapped during 30 min of no-flow ischemia. Altering Na+ and Ca2+ did not substantially affect baseline conduction. Increasing Na+ and decreasing Ca2+ both lowered pacing thresholds, whereas increasing Ca2+ narrowed perinexal width (Wp). A least squares mean estimate revealed that reduced perfusate Na+ and Ca2+ resulted in the most severe conduction slowing during is...Continue Reading

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Citations

Mar 5, 2021·Pflügers Archiv : European journal of physiology·D Ryan KingSteven Poelzing
Sep 18, 2021·Journal of Cardiovascular Pharmacology and Therapeutics·Demetria M FischesserKevin J Haworth
Oct 9, 2021·American Journal of Physiology. Heart and Circulatory Physiology·Xiaobo WuSteven Poelzing

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Methods Mentioned

BETA
Protein Assay
transmission electron microscopy
electron microscopy

Software Mentioned

R
ImageJ
GraphPad Prism
clinfun package
LabChart
MatLab

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