The conduction velocity-potassium relationship in the heart is modulated by sodium and calcium.

The relationship between cardiac conduction velocity (CV) and extracellular potassium (K) is biphasic, with modest hyperkalemia increasing CV and severe hyperkalemia slowing CV. Recent studies from our group suggest that elevating extracellular sodium (Na) and calcium (Ca) can enhance CV by an extracellular pathway parallel to gap junctional coupling (GJC) called ephaptic coupling that can occur in the gap junction adjacent perinexus. However, it remains unknown whether these same interventions modulate CV as a function of K.

Modulating cardiac conduction during metabolic ischemia with perfusate sodium and calcium in guinea pig hearts.

We previously demonstrated that altering extracellular sodium (Na) and calcium (Ca) can modulate a form of electrical communication between cardiomyocytes termed "ephaptic coupling" (EpC), especially during loss of gap junction coupling. We hypothesized that altering Na and Ca modulates conduction velocity (CV) and arrhythmic burden during ischemia. Electrophysiology was quantified by optically mapping Langendorff-perfused guinea pig ventricles with modified Na (147 or 155 mM) and Ca (1.

Design and validation of a tissue bath 3-D printed with PLA for optically mapping suspended whole heart preparations.

With the sudden increase in affordable manufacturing technologies, the relationship between experimentalists and the designing process for laboratory equipment is rapidly changing. While experimentalists are still dependent on engineers and manufacturers for precision electrical, mechanical, and optical equipment, it has become a realistic option for in house manufacturing of other laboratory equipment with less precise design requirements. This is possible due to decreasing costs and increasing functionality of desktop three-dimensional (3-D) printers and 3-D design software.

Heart Rate and Extracellular Sodium and Potassium Modulation of Gap Junction Mediated Conduction in Guinea Pigs.

Background: Recent studies suggested that cardiac conduction in murine hearts with narrow perinexi and 50% reduced connexin43 (Cx43) expression is more sensitive to relatively physiological changes of extracellular potassium ([K(+)]o) and sodium ([Na(+)]o).

Purpose: Determine whether similar [K(+)]o and [Na(+)]o changes alter conduction velocity (CV) sensitivity to pharmacologic gap junction (GJ) uncoupling in guinea pigs.

Methods: [K(+)]o and [Na(+)]o were varied in Langendorff perfused guinea pig ventricles (Solution A: [K(+)]o = 4.