Inwardly rectifying chloride channel activity in intestinal pacemaker cells.
Cl(-) channels are proposed to play a role in gut pacemaker activity, but little is known about the characteristics of Cl(-) channels in interstitial cells of Cajal (ICC), the intestinal pacemaker cells. The objective of the present study was to identify whole cell Cl(-) currents in ICC associated with previously observed single-channel activity and to characterize its inward rectification. Whole cell patch-clamp studies showed that ICC express an inwardly rectifying Cl(-) current that was not sensitive to changes in cation composition of the extracellular solutions. Currents were not affected by replacing all cations with N-methyl-d-glucamine (NMDG(+)). Whole cell currents followed the Cl(-) equilibrium potential and were inhibited by DIDS and 9-anthracene carboxylic acid. Ramp protocols of single-channel activity showed that inward rectification was due to reduction in single-channel open probability, not a reduction in single-channel conductance. Single-channel data led to the hypothesis that strong cooperation exists between 30-pS channels that show less cooperation at potentials positive to the reversal potential. Hence, an inwardly rectifying Cl(-) channel plays a prominent role in determining pacemaker activity in the gut.
Zhu
Yaohui
Y
McMaster Univ., HSC-3N5C, 1200 Main St. West, Hamilton, ON L8N 3Z5, Canada.
Mucci
Andrea
A
Huizinga
Jan D
JD
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000818:Animals; D000838:Anions / Q000378:metabolism; D000873:Anthracenes / Q000494:pharmacology; D001683:Biological Clocks / Q000502:physiology*; D002412:Cations / Q000378:metabolism; D002478:Cells, Cultured; D018118:Chloride Channels / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004553:Electric Conductivity; D004558:Electric Stimulation / Q000379:methods; D007583:Jejunum / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D051379:Mice; D008815:Mice, Inbred Strains
D000838:Anions; D000873:Anthracenes; D002412:Cations; D018118:Chloride Channels; C010030:9-anthroic acid; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid