Résumé
Membrane electrical properties of freshly isolated rat osteoclasts were studied using patch-clamp recording methods. Characterization of the passive membrane properties indicated that the osteoclast cell membrane behaved as an isopotential surface. The specific membrane capacitance was 1.2±0.3 μF/cm2 (mean ±SD), with no difference between cells plated on glass and those adhering to a permeable collagen substrate. The current/voltage (I/V) relationship of all cells showed inward rectification and I/V curves shifted 51 mV positive per tenfold increase of [K+]out, indicating an inwardly rectifying K+ conductance. The voltage dependence of the K+ chord conductance (gK) also shifted positive along the voltage axis, and the maximum conductance increased, with elevation of [K+]out. gK for cells bathed in 4.7 mM [K+]out increased e-fold per 12mV hyperpolarization, and half-maximal activation was at -89 mV. Approximately 18% (50 pS/pF) of the maximum gK was active at -70 mV. Inward single-channel currents were recorded in cell-attached patches at hyperpolarizing potentials. With symmetrical K+, channel conductance was 25±3 pS and reversal was close to the K+ equilibrium potential, consistent with this K+ channel underlying the whole-cell K+ currents. With both conventional whole-cell and perforated-patch recording, no voltage-activated Ca2+ current was detected. In approximately 30% of osteoclasts studied, an outwardly rectifying current was observed, which was reversibly blocked by 4,4′-diisothiocyanostilbene-2,2′-disulphonic acid (DIDS) and 4-acetamido-4′-isothiocyanostilbene2,2′-disulphonic acid (SITS). This DIDS- and SITS-sensitive current reversed direction at the chloride equilibrium potential. We conclude that an inwardly rectifying K+ current is present in all rat osteoclasts and that some osteoclasts also exhibit an outwardly rectifying Cl- current. Both these membrane conductances may play an important physiological role by dissipating the potential that arises from the electrogenic transport of H+ across the ruffled membrane of the osteoclast.
Langue d'origine | English |
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Pages (de-à) | 358-370 |
Nombre de pages | 13 |
Journal | Pflugers Archiv European Journal of Physiology |
Volume | 419 |
Numéro de publication | 3-4 |
DOI | |
Statut de publication | Published - oct. 1991 |
Publié à l'externe | Oui |
ASJC Scopus Subject Areas
- Physiology
- Clinical Biochemistry
- Physiology (medical)