Abstract
Whole-cell and inside-out patch-clamp techniques were used to assess the action of a well-known dye, Evans blue, on membrane currents in bladder isolated smooth muscle cells from sheep. In whole cells Evans blue dose-dependently increased the outward current by up to fivefold. In contrast, Evans blue had no effect on inward Ca2+ current. The effect on outward current was abolished or reduced if the cells were bathed in Ca2+-free solution, iberiotoxin (5 × 10–8 M), or charybdotoxin (5 × 10–8 M), but was unaffected by externally applied caffeine (5 mM) or in cells exposed to heparin (1 mg/ml) via the patch pipette. In inside-out patches bathed in a Ca2+ concentration of 5 × 10–7 M, Evans blue (10–4 M) increased the open probability of large-conductance (298-pS) Ca2+-dependent K+ channels (BK channels), shifting the half maximal-activation voltage by –70 mV. We conclude that Evans blue dye acts as an opener of BK channels.
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Received: 1 September 1997 / Received after revision: 18 November 1997 / Accepted: 20 November 1997
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Hollywood, M., Cotton, K., McHale, N. et al. Enhancement of Ca2+-dependent outward current in sheep bladder myocytes by Evans blue dye. Pflügers Arch 435, 631–636 (1998). https://doi.org/10.1007/s004240050563
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DOI: https://doi.org/10.1007/s004240050563