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Properties of Single Voltage-gated Proton Channels in Human Eosinophils Estimated by Noise Analysis and by Direct Measurementстатья
Информация о цитировании статьи получена из
Web of Science,
Scopus
Дата последнего поиска статьи во внешних источниках: 4 января 2018 г.
- Авторы: Cherny Vladimir V., Murphy Ricardo, Sokolov Valerij, Levis Richard A., DeCoursey Thomas E.
- Журнал: The Journal of General Physiology
- Том: 121
- Номер: 6
- Год издания: 2003
- Первая страница: 615
- Последняя страница: 628
- DOI: 10.1085/jgp.200308813
- Аннотация: Voltage-gated proton channels were studied under voltage clamp in excised, inside-out patches of human eosinophils, at various pHi with pHo 7.5 or 6.5 pipette solutions. H current fluctuations were observed consistently when the membrane was depolarized to voltages that activated H current. At pHi 5.5 the variance increased nonmonotonically with depolarization to a maximum near the midpoint of the H conductance-voltage relationship, gH-V, and then decreased, supporting the idea that the noise is generated by H channel gating. Power spectral analysis indicated Lorentzian and 1/f components, both related to H currents. Unitary H current amplitude was estimated from stationary or quasi-stationary variance, . We analyze data obtained at various voltages on a linearized plot that provides estimates of both unitary conductance and the number of channels in the patch, without requiring knowledge of open probability. The unitary conductance averaged 38 fS at pHi 6.5, and increased nearly fourfold to 140 fS at pHi 5.5, but was independent of pHo. In contrast, the macroscopic gH was only 1.8-fold larger at pHi 5.5 than at pHi 6.5. The maximum H channel open probability during large depolarizations was 0.75 at pHi 6.5 and 0.95 at pHi 5.5. Because the unitary conductance increases at lower pHi more than the macroscopic gH, the number of functional channels must decrease. Single H channel currents were too small to record directly at physiological pH, but at pHi 5.5 near V threshold (the voltage at which gH turns on), single channel-like current events were observed with amplitudes 7-16 fA.
- Добавил в систему: Соколов Валерий Сергеевич