Local Membrane Deformations Activate Ca2+-Dependent K+ and Anionic Currents in Intact Human Red Blood Cells
Figure 4
Identification of Gardos channels.
(A and B) Patch-clamp single-channel recordings (representative of 25 and 19 experiments, respectively) and corresponding I/V relationships of red blood cell membrane electrical activity obtained (A) with solution B (150 mM KCl, pCa3) in the pipette and solution B in bath, and (B) with solution B in bath and solution A (150 mM NaCl, pCa3) in the pipette. The inset displays the corresponding evolution of the open probabilities (Po)(Closed symbols: panel A; open symbols: panel B). Panels C and D show, at 0 mV and −40 mV pipette potentials, inhibition of channel activity by clotrimazole (C: control; D: clotrimazole added to the bathing solution at a concentration of 10 µmol/l)(representative of 8 experiments). Requirement of extracellular calcium for activation of Gardos channels is demonstrated in Panel E (representative of 11 experiments) by almost total absence of channel activity whatever the imposed pipette potential (0 mV and −40 mV in the presented recordings) when the bathing solution was solution A (150 mM NaCl) adjusted to pCa7 and pipettes contained solution B (150 mM KCl) adjusted to pCa7.