Key result
Intracellular pH and transjunctional voltage independently gate gap junction conductance via separate macromolecular regions.
Why the study?
The mechanisms by which transjunctional voltage and intracellular pH gate gap junctional conductance in vertebrate embryos were unclear and needed investigation.
The mechanisms by which intracellular pH and transjunctional voltage gate gap junctional conductance in amphibian embryonic cells are independent and likely involve separate regions of the junctional macromolecules.
Does not support changes in clinical practice for arrhythmias; leaves open whether independent pH and voltage gating extends to mammalian cardiomyocytes.
In vertebrate embryos gap junctional conductance (gj) is reduced by transjunctional voltage (Vj) and by cytoplasmic acidification; in each case sensitivity is comparable to those of other channels gated by voltage and ligand-receptor binding. We show here that the mechanisms by which Vj and intracellular pH (pHi) gate gj are apparently independent. Partial reduction of gj by lowering pHi neither attenuates nor enhances further reduction by Vj. Certain drugs irreversibly (glutaraldehyde, 1-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline) or reversibly (retinoic acid) abolish dependence of gj on pHi without appreciably affecting kinetic properties of voltage dependence or the shape of the steady-state Vj-gj relation. These findings suggest that the mechanisms by which pHi and Vj act on the gap junction are at least partially distinct and presumably involve separate regions of the junctional macromolecules.
No takes yet. Share an insight, caveat, or question.
Spray et al. (1986) studied this question. Intracellular pH and transjunctional voltage was evaluated on Gap junctional conductance (gj). The mechanisms by which intracellular pH and transjunctional voltage gate gap junctional conductance in amphibian embryonic cells are independent and involve separate regions of the macromolecules.
Synapse has enriched 4 closely related papers on similar clinical questions. Consider them for comparative context: