The non-selective voltage-activated cation channel in the human red blood cell membrane: reconciliation between two conflicting reports and further characterisation |
| |
Authors: | Kaestner L Christophersen P Bernhardt I Bennekou P |
| |
Institution: | Biophysics Section, Institute of Biology, Humboldt University Berlin, Germany. |
| |
Abstract: | Using the patch-clamp technique, the non-selective, voltage-activated cation channel in the human red blood cell (RBC) membrane was further characterised. Activity of the cation channel could be demonstrated at a range of salt concentrations with the current-voltage characteristics for monovalent cations going from linear to superlinear functions, depending on the cation concentration in the range of 100-500 mM. The non-selective voltage-activated cation channel was demonstrated to be permeable to the divalent cations Ca2+ and Ba2+, and even Mg2+. The current-voltage relations for the divalent cations were superlinear even at 75 mM salt concentration, but indicated outward rectification in contrast to the I-V curve for monovalent cations. The degree of activation at a given membrane potential depended strongly on the prehistory of the channel. The gating exhibited hysteretic-like behaviour, since the quasi steady-state deactivation and activation curves were displaced by approximately 25 mV. This result fully explains apparent discrepancies between V0.5-values previously obtained by slightly different experimental protocols. The possible physiological/pathophysiological role of the channel is discussed in the context of the demonstrated permeability for divalent cations. |
| |
Keywords: | |
本文献已被 PubMed 等数据库收录! |
|