Characterization of outward K(+) currents in isolated smooth muscle cells from sheep urethra.

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

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)

Abstract

The perforated-patch technique was used to measure membrane currents in smooth muscle cells from sheep urethra. Depolarizing pulses evoked large transient outward currents and several components of sustained current. The transient current and a component of sustained current were blocked by iberiotoxin, penitrem A, and nifedipine but were unaffected by apamin or 4-aminopyridine, suggesting that they were mediated by large-conductance Ca(2+)-activated K(+) (BK) channels. When the BK current was blocked by exposure to penitrem A (100 nM) and Ca(2+)-free bath solution, there remained a voltage-sensitive K(+) current that was moderately sensitive to blockade with tetraethylammonium (TEA; half-maximal effective dose = 3.0 +/- 0.8 mM) but not 4-aminopyridine. Penitrem A (100 nM) increased the spike amplitude and plateau potential in slow waves evoked in single cells, whereas addition of TEA (10 mM) further increased the plateau potential and duration. In conclusion, both Ca(2+)-activated and voltage-dependent K(+) currents were found in urethral myocytes. Both of these currents are capable of contributing to the slow wave in these cells, suggesting that they are likely to influence urethral tone under certain conditions.
Original languageEnglish
Pages (from-to)C420-428
Number of pages9
JournalAmerican Journal of Physiology - Cell Physiology
Volume279(2)
Issue number2 48-2
Publication statusPublished - 2000

ASJC Scopus subject areas

  • Cell Biology
  • Clinical Biochemistry
  • Physiology
  • Physiology (medical)

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