Effect of purinergic blockers on outward current in isolated smooth muscle cells of the sheep bladder

Karen McCloskey, M Hollywood, K Thornbury, Noel McHale

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12 Citations (Scopus)


Freshly dispersed cells from sheep urinary bladder were voltage clamped using the whole cell and inside-out patch-clamp technique. Cibacron and Basilen blue increased outward current in a dose-dependent manner with a half-maximal response at 10(-5) M. Suramin, in concentrations to 10(-3) M, had no such effect. The Cibacron blue response was abolished in Ca2+-free physiological salt solution, suggesting that it was acting on a Ca2+-dependent current. Similarly, the Cibacron blue-sensitive current was significantly attenuated by charybdotoxin. Cibacron blue did not modulate inward current nor were its effects modified by caffeine or heparin, suggesting that its effect on outward current was not secondary to an increase in intracellular Ca2+. Application of 10(-4) M Cibacron blue to the inside membrane of excised patches caused a rapid increase in open probability of a large-conductance (300 pS) K+ channel. These results suggest that Cibacron blue is a potent activator of a Ca2+-dependent outward current in bladder smooth muscle cells in addition to its action as a purinergic blocker.

Original languageEnglish
Pages (from-to)C969-C973
Number of pages5
JournalAmerican Journal of Physiology - Cell Physiology
Issue number3
Publication statusPublished - Mar 1996


  • Cibacron blue
  • Reactive blue 2
  • potassium channel opener
  • calcium-activated potassium channels


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