Electrophysiological demonstration of voltage- activated H+ channels in bovine articular chondrocytes.
Matrix synthesis by articular chondrocytes is sensitive to changes in intracellular pH (pH(i)), so characterising the membrane transport pathways that determine pH(i) is important for understanding how chondrocytes regulate the turnover of cartilage matrix. In the present study, the whole-cell patch-clamp technique has been employed to demonstrate the operation of voltage-activated H(+) channels (VAHC) in bovine articular chondrocytes. Using solutions designed to minimise the contribution of ions other than H(+), the application of step voltage-protocols elicited whole-cell currents. These currents were slow activating, observed only in the outward direction, dependent on both extracellular pH (pH(o)) and pH(i), and inhibited by Zn(2+). The reversal potential values, measured by tail current analysis, over a range of different pHo and pHi values, were in good agreement with predicted values for membrane channels having a high selectivity for protons. The results presented here are consistent with the operation of VAHC in articular chondrocytes.
Sánchez
Julio C
JC
Universidad Tecnológica de Pereira, Departamento de Ciencias Básicas - Facultad de Ciencias de la alud, A.A. 97 - La Julita, Pereira - Risaralda - Colombia.
Powell
Trevor
T
Staines
Henry M
HM
Wilkins
Robert J
RJ
D000818:Animals; D002358:Cartilage, Articular / Q000166:cytology; D002417:Cattle; D019902:Chondrocytes / Q000166:cytology / Q000502:physiology*; D004594:Electrophysiology / Q000379:methods; D006863:Hydrogen-Ion Concentration; D015640:Ion Channel Gating / Q000502:physiology; D007473:Ion Channels / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D018408:Patch-Clamp Techniques; D015032:Zinc / Q000494:pharmacology
D007473:Ion Channels; D015032:Zinc