Membrane currents and cholinergic regulation of K+ current in esophageal smooth muscle cells

S. M. Sims, M. B. Vivaudou, C. Hillemeier, P. Biancani, J. V. Walsh, J. J. Singer

Research output: Contribution to journalArticlepeer-review

31 Scopus citations

Abstract

The tight-seal whole cell recording technique with patch pipettes was used to study membrane currents of smooth muscle cells freshly dissociated from the esophagus of cats. Under voltage clamp with K+ in the pipette, depolarizing commands elicited an initial inward current followed by a transient outward current that peaked and then declined to reveal spontaneous outward currents (SOCs). SOCs were evident at -60 mV and more positive potentials. The reversal of SOCs at the K+ equilibrium potential and their suppression by tetraethylammonium chloride lead to the conclusion that they represent the activity of K+ channels. Acetylcholine (ACh) caused reversible contraction of these cells and had two successive effects on membrane currents, causing transient activation of K+ current followed by suppression of SOCs. Both of these effects were blocked by atropine. Consistent with these observations, in current clamp, ACh caused a transient hyperpolarization followed by depolarization. The inward current activated by depolarization was blocked by external Cd2+, consistent with the inward current being a voltage-activated calcium current. Two types of Ca2+ current could be distinguished on the basis of voltage-activation range, time course of inactivation and 'run-down' during whole cell recording.

Original languageEnglish (US)
Pages (from-to)G794-G802
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Volume258
Issue number5 21-5
DOIs
StatePublished - 1990

All Science Journal Classification (ASJC) codes

  • Physiology
  • Hepatology
  • Gastroenterology
  • Physiology (medical)

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