A voltage-activated proton current in human cardiac fibroblasts.
A voltage-activated proton current in human cardiac fibroblasts, measured using the whole-cell recording configuration of the patch-clamp technique, is reported. Increasing the pH of the bathing solution shifted the current activation threshold to more negative potentials and increased both the current amplitude and its rate of activation. Changing the pH gradient by one unit caused a 51mV shift in the reversal potential of the current, demonstrating a high selectivity for protons of the channel carrying the current. Extracellularly applied Zn(2+) reversibly inhibited the current. Activation of the current contributes to the resting membrane conductance under conditions of intracellular acidosis. It is proposed that this current in cardiac fibroblasts is involved in the regulation of the intracellular pH and the membrane potential under physiological conditions as well as in response to pathological conditions such as ischemia.
El Chemaly
Antoun
A
Institut de Physiologie et Biologie Cellulaires, UMR CNRS 6187, Université de Poitiers, 40 avenue du Recteur Pineau 86022 Poitiers Cedex, France.
Guinamard
Romain
R
Demion
Marie
M
Fares
Nassim
N
Jebara
Victor
V
Faivre
Jean-François
JF
Bois
Patrick
P
D000328:Adult; D000368:Aged; D002478:Cells, Cultured; D005347:Fibroblasts / Q000378:metabolism* / Q000502:physiology; D006801:Humans; D008564:Membrane Potentials / Q000502:physiology; D009206:Myocardium / Q000166:cytology* / Q000378:metabolism*; D018408:Patch-Clamp Techniques / Q000379:methods; D011522:Protons
D011522:Protons