In:
Journal of Experimental Biology, The Company of Biologists, Vol. 210, No. 14 ( 2007-07-15), p. 2489-2500
Abstract:
A chloride current, ICl,H, slowly activating on hyperpolarisation was investigated in Drosophila melanogaster larval muscles using the two-electrode voltage clamp. Sizeable currents were observed after the intracellular chloride concentration([Cl–]i) had been elevated by diffusion of Cl– from the electrodes. The time course of ICl,H was rather variable and required two exponentials to be accurately described. The reversal potential, –40 to –20 mV in Cl–-loaded fires, shifted on lowering external[Cl–] in the positive direction. Steady-state activation of ICl,H was characterised by V0.5 of≈–120 mV and a slope factor, k, of ≈10 mV at a[Cl–]i ≈35 mmol l–1. Raising[Cl–] i to ≈50 mmol l–1 caused a negative shift of V0.5 equivalent to the change of ECl and led to a nearly threefold increase in maximal steady-state conductance. ICl,H was resistant to 10 mmol l–1 Zn2+ and 1 mmol l–1Cd2+ but was greatly reduced by 1 mmol l–19-anthracenecarboxylic acid (9-AC). ICl,H was affected by changes of extracellular pH and increased on lowering extracellular osmolality. 9-AC also decreased muscle fibre resting conductance by approximately 20% and increased muscle contractions. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis confirmed the expression of all three ClC genes in muscle, and immunohistochemistry indicated location of Drosophila melanogaster chloride channel-2(DmClC-2) at the Z-lines. We conclude that DmClC-2 accounts for the channels underlying ICl,H, and in part for the resting chloride conductance. DmClC-2 may serve general homeostatic mechanisms such as pH- and osmo-regulation or may support muscle function on high motor activity or during a particular neurohormonal state of the animal.
Type of Medium:
Online Resource
ISSN:
1477-9145
,
0022-0949
Language:
English
Publisher:
The Company of Biologists
Publication Date:
2007
detail.hit.zdb_id:
1482461-9
SSG:
12
