Ca -activated Cl current in cultured myenteric neurons from murine proximal colon

Kang, Sok Han, Pieter Vanden Berghe, and Terence K. Smith. Ca2 -activated Cl current in cultured myenteric neurons from murine proximal colon. Am J Physiol Cell Physiol 284: C839–C847, 2003. First published November 27, 2002; 10.1152/ajpcell.00437.2002.—Whole cell patchclamp 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 (Itdo), whereas repolarization was followed by a slowly deactivating tail current (Itail). Itdo and Itail were present in 70% of neurons. We identified these currents as Cl currents (ICl), because changing the transmembrane Cl gradient altered the measured reversal potential (Erev) of both Itdo and Itail with that for Itail shifted close to the calculated Cl equilibrium potential (ECl). ICl are Ca2 -activated Cl current [ICl(Ca)] because they were Ca2 dependent. ECl, which was measured from the Erev of ICl(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 . -Conotoxin GIVA [0.3 M; N-type Ca2 channel blocker] and niflumic acid [10 M; known ICl(Ca) blocker], decreased the ICl(Ca). In conclusion, these neurons have ICl(Ca) that are activated by Ca2 entry through N-type Ca2 channels. These currents likely regulate postspike frequency adaptation.