H. Kajita et al., The chloride channel ClC-2 contributes to the inwardly rectifying Cl- conductance in cultured porcine choroid plexus epithelial cells, J PHYSL LON, 523(2), 2000, pp. 313-324
The contribution of ClC-2 protein to the inwardly rectifying Cl- conductanc
e in cultured porcine choroid plexus epithelial cells was investigated usin
g Western analysis and whole-cell current recordings.
Inwardly rectifying currents were elicited by hyperpolarizing voltage at a
potential more negative than -50 mV in the presence of intracellular protei
n kinase A (PKA). The relative halide selectivity estimated from the shift
in the reversal potential (E-rev) was I- > Br- > Cl- > F-.
Extracellular vasoactive intestinal peptide (VIP) activated the same curren
ts in a dose-dependent manner with a half-maximal concentration of 167.3 nM
. H-89 (a PKA inhibitor) interfered with the current activation by VIP.
The Cl- channel was inhibited by external Cd2+, B2+ or H+, but only weakly
inhibited by known Cl- channel blockers including glibenclamide, NPPB, DIDS
and anthracene-9-carboxylic acid (SAC).
A specific antibody to ClC-2 detected a 79 kDa protein in porcine choroid p
lexus cells, which was reduced in cells treated with antisense oligodeoxynu
cleotide for ClC-2. Both PKA and VIP failed to activate the inwardly rectif
ying Cl- currents in cells transfected with the antisense oligodeoxynucleot
ide, while they activated the currents in cells transfected with GFP alone
or the control oligodeoxynucleotide randomized from antisense oligonucleoti
de.
It is concluded that ClC-2 protein contributes to the inwardly rectifying C
l- conductance in porcine choroid plexus epithelial cells.