Activation of Ca(2+)‐dependent Cl‐ currents in cultured rat sensory neurones by flash photolysis of DM‐nitrophen.

Abstract

1. Voltage-gated Ca2+ currents (ICa) and Ca2+-activated Cl-currents (Icl(ca)) were recorded from cultured rat dorsal root ganglion (DRG) neurones using the whole-cell configuration of the patch clamp technique. Intracellular photorelease of Ca2+ by flash photolysis of DM-nitrophen elicited transient inward currents only in those cells which possessed Ca2+_ activated Cl-tail currents following ICa. The reversal potential of the flash responses was hyperpolarized when extracellular Cl-was replaced by SCN-. The flash responses and the Ca2+-activated Cl-tail currents were inhibited by the Cl-channel blockers niflumic acid (10-100 /SM) and 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB) (10 /1M).

KW-7158 [(2S)-(+)-3,3,3-Trifluoro-2-hydroxy-2-methyl-N-(5,5,10-trioxo-4,10-dihydrothieno[3,2-c][1]benzothiepin-9-yl)propanamide] Enhances A-Type K+ Currents in Neurons of the Dorsal Root Ganglion of the Adult Rat

“…1A), it elicited a membrane hyperpolarization that was detectable at a concentration of 0.05 M and maximal (5-10 mV) at concentrations ranging from 0.1 to 1 M (n ϭ 20 cells tested). Because a depolarization would be expected if Cl Ϫ channels were activated by KW-7158 near the RP of DRG neurons (Currie et al, 1995;England et al, 2001), the most likely explanation for this effect is that KW-7158 activated a K ϩ channel. At higher concentrations of KW-7158 (1-500 M), the hyperpolarization was attenuated (Fig.…”

A cyclic GMP‐dependent housekeeping Cl− channel in rabbit gastric parietal cells activated by a vasodilator ecabapide

“…It is noted that the Cl-currents in both cases were not significantly inhibited by niflumic acid, which is established as an inhibitor of Ca2+-activated Cl-currents (White & Aylwin, 1990;Korn et al, 1991;Hogg et al, 1994;Currie et al, 1995) and cyclic AMP-activated Cl-currents (Hughes & Segawa, 1993).…”

Modulation of Ca2+‐dependent currents in metabolically stressed cultured sensory neurones by intracellular photorelease of ATP

“…One mM 'caged' ATP (adenosine-5'-triphosphate, P3-1-(2-nitrophenyl) ethyl ester) or 100 tM 'caged' cyclic AMP (adenosine-3':5'-cyclic monophosphate Pl-(2-nitrophenyl) ethyl ester: axial isomer) were included in the patch pipette solution in this study. (Walker et al, 1988;Currie et al, 1995). The 'caged' compounds were synthesized and characterized by previously published methods (Walker et al, 1988;Wootton & Trentham, 1989).…”

“…Calcium-activated Cl-currents appear not to inactivate but gradually deactivate when intracellular Ca2" declines (Currie et al, 1995;Scott et al, 1995). Therefore as part of the study we have used Ca2"-activated Cl-tail currents as a physiological index of Ca2" concentration close to the plasma membrane to gain an insight into the ability of cells to handle Ca2" which has entered the cultured neurones through voltage-activated Ca2" channels.…”