Ca 2+ -activated Cl − current in cultured myenteric neurons from murine proximal colon

• Published in: American Journal of Physiology: Cell Physiology 2003-04, Vol.284 (4), p.C839-C847
• Main Authors: Kang, Sok Han, Vanden Berghe, Pieter, Smith, Terence K.
• Format: Article
• Language: English
• ISSN: 0363-6143; 1522-1563
• DOI: 10.1152/ajpcell.00437.2002

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 ∼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 − . ω-Conotoxin GIVA [0.3 μM; N-type Ca 2+ channel blocker] and niflumic acid [10 μM; 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.