Ca²⁺-activated Cl⁻ current in cultured myenteric neurons from murine proximal colon

Abstract

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.

Anoctamins and gastrointestinal smooth muscle excitability

“…It is possible, therefore, that cells other than ICC (e.g. enteric neurons, which display Ca 2+ ‐activated Cl − currents; Kang et al 2003) might express other Tmem16 paralogues, and gene products may be responsible for the Cl ‐ conductances in these cells. Interstitial cells of Cajal may also express paralogues in addition to Tmem16a ; however, as shown below, Tmem16a appears to be the dominant conductance driving slow waves in ICC.…”

R-type calcium channels in myenteric neurons of guinea pig small intestine

“…N-type channels. There is a CTX-sensitive component to calcium current recorded from guinea pig, rat, and mouse enteric neurons (2,5,10,20,42,46). In addition, Ca V 2.2 is expressed by enteric neurons from guinea pigs and rats (21,52).…”

Mechanism of butyrate‐induced hyperpolarization of cultured rat myenteric neurones

“…It might be caused by a stimulation of Ca 2+ ‐dependent Cl − channels, which are known e.g. from murine myenteric neurones, 21 a response which would drive the membrane potential closer to the Cl − equilibrium potential (−32.8 mV at our conditions with 44 mmol L −1 Cl − in the pipette solution and 149.9 mmol L −1 Cl − in the superfusion medium). However, due to the inconsistent nature of this secondary phase, this phenomenon was not examined further.…”