Enhancement of Ca2+-dependent outward current in sheep bladder myocytes by evans blue dye.

M.A. Hollywood, Karen McCloskey, N.G. McHale, K.D. Thornbury

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)

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 x 10(-8) M), or charybdotoxin (5 x 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 x 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.
Original languageEnglish
Pages (from-to)631-636
Number of pages6
JournalPflugers Archiv : European journal of physiology
Volume435(5)
Issue number5
Publication statusPublished - 1998

ASJC Scopus subject areas

  • Physiology

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