Ca2+-activated Cl- current in cultured myenteric neurons from murine proximal colon |
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Authors: | Kang Sok Han Vanden Berghe Pieter Smith Terence K |
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Institution: | Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada 89557, USA. |
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Abstract: | Whole cell patch-clamprecordings were made from cultured myenteric neurons taken from murineproximal colon. The micropipette contained Cs+ to removeK+ currents. Depolarization elicited a slowly activatingtime-dependent outward current (Itdo), whereasrepolarization was followed by a slowly deactivating tail current(Itail). Itdo andItail were present in ~70% of neurons. Weidentified these currents as Cl currents(ICl), because changing the transmembraneCl gradient altered the measured reversal potential(Erev) of both Itdo andItail with that for Itailshifted close to the calculated Cl equilibrium potential(ECl). ICl areCa2+-activated Cl currentICl(Ca)] because they were Ca2+dependent. ECl, which was measured from theErev of ICl(Ca) using agramicidin perforated patch, was 33 mV. This value is more positivethan the resting membrane potential ( 56.3 ± 2.7 mV), suggestingmyenteric neurons accumulate intracellular Cl . -Conotoxin GIVA 0.3 µM; N-type Ca2+ channelblocker] and niflumic acid 10 µM; knownICl(Ca) blocker], decreased theICl(Ca). In conclusion, these neurons haveICl(Ca) that are activated by Ca2+entry through N-type Ca2+ channels. These currents likelyregulate postspike frequency adaptation. |
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