Evidence for spontaneous channel activity following seal formation.

<p>Patch-clamp single-channel recordings of red blood cell spontaneous membrane electrical activity (<i>i.e.</i> in absence of pipette potential: -Vp = 0 mV) indicating an inwardly directed movement of cations or an outward movement of anions during the first 10 min following seal formation. Seals were obtained by underpressure inducing membrane deformation in the patch pipette. Panel <b>A</b> shows two typical recordings obtained with solution A (150 mM NaCl, pCa3) in the pipette and bathing solutions. Long channel openings are followed by long silent intervals. (<b>B</b>) shows four different recordings, obtained with solution B (150 mM KCl, pCa3) in the pipette solution and solution A (150 mM NaCl, pCa 3) in bathing solution. Dashed lines indicate the baseline corresponding to the closed state. Panel <b>C</b> presents an example of I/V plot obtained when 1 min ramps of depolarizng or hyperpolarizing voltages were imposed in the pipette in the following order: (in mV) 0, −10, +10, −20, +20, −30, +30, −40, +40, immediately following seal formation. This V-shaped I/V curve suggests a continuous decline with time in channel activity.