Ca2+-activated Cl- current in cultured myenteric neurons from murine proximal colon.
Whole cell patch-clamp recordings were made from cultured myenteric neurons taken from murine proximal colon. The micropipette contained Cs(+) to remove K(+) currents. Depolarization elicited a slowly activating time-dependent outward current (I(tdo)), whereas repolarization was followed by a slowly deactivating tail current (I(tail)). I(tdo) and I(tail) were present in approximately 70% of neurons. We identified these currents as Cl(-) currents (I(Cl)), because changing the transmembrane Cl(-) gradient altered the measured reversal potential (E(rev)) of both I(tdo) and I(tail) with that for I(tail) shifted close to the calculated Cl(-) equilibrium potential (E(Cl)). I(Cl) are Ca(2+)-activated Cl(-) current [I(Cl(Ca))] because they were Ca(2+) dependent. E(Cl), which was measured from the E(rev) of I(Cl(Ca)) using a gramicidin perforated patch, was -33 mV. This value is more positive than the resting membrane potential (-56.3 +/- 2.7 mV), suggesting myenteric neurons accumulate intracellular Cl(-). omega-Conotoxin GIVA [0.3 microM; N-type Ca(2+) channel blocker] and niflumic acid [10 microM; known I(Cl(Ca)) blocker], decreased the I(Cl(Ca)). In conclusion, these neurons have I(Cl(Ca)) that are activated by Ca(2+) entry through N-type Ca(2+) channels. These currents likely regulate postspike frequency adaptation.
Kang
Sok Han
SH
Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada 89557, USA.
Vanden Berghe
Pieter
P
Smith
Terence K
TK
D000818:Animals; D002118:Calcium / Q000502:physiology*; D020864:Calcium Channels, N-Type / Q000502:physiology; D002478:Cells, Cultured; D018118:Chloride Channels / Q000037:antagonists & inhibitors / Q000502:physiology*; D003106:Colon / Q000294:innervation*; D025802:Electric Capacitance; D004553:Electric Conductivity; D008564:Membrane Potentials; D051379:Mice; D009197:Myenteric Plexus / Q000166:cytology / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D009544:Niflumic Acid / Q000494:pharmacology
D020864:Calcium Channels, N-Type; D018118:Chloride Channels; D009544:Niflumic Acid; D002118:Calcium