Heat-stable toxin from Escherichia coli activates chloride current via cGMP-dependent protein kinase

Meiqiu Lin, Katrina Macleod, Sandra Guggino

Research output: Contribution to journalArticle

Abstract

Heat-stable toxin (STa) increases cyclic GMP (cGMP) in iso- lated intestinal cells and in T84 cells, a colonic secretory cell line. Whole-cell current recordings from patch clamp experiments show identical properties for currents activated by either STa or the cystic fibrosis transmembrane conductance regulator (CFTR) channel. STa-activated currents display a linear current-voltage relationship and a relative permeability sequence of Br > Cl > I. STa or 8-Br-cGMP-activated currents remain when 20μM Walsh inhibitor, a blocker of protein kinase A (PKA), is added in the pipette, suggesting that cGMP-dependent protein kinase (PKG) activates the currents. Intracellular addition of Rp-8-Br-cGMP, an agent that activates PKGII and inhibits PKGI and PKA, causes induction of a chloride conductance identical to that stimulated by STa. We conclude that STa activates CFTR by phosphorylation with cGMP-dependent protein kinase.

Original languageEnglish (US)
Pages (from-to)23-32
Number of pages10
JournalCellular Physiology and Biochemistry
Volume5
Issue number1
DOIs
StatePublished - Jan 1 1995

Keywords

  • Channel
  • Diarrhea
  • Intestine
  • Kinase
  • T84 cells

ASJC Scopus subject areas

  • Physiology

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