Hc. Chan et al., CHARACTERIZATION OF A SWELLING-INDUCED CHLORIDE CONDUCTANCE IN CULTURED RAT EPIDIDYMAL CELLS, The American journal of physiology, 265(4), 1993, pp. 30000997-30001005
Swelling-induced Cl conductance in cultured rat epididymal cells was c
haracterized using whole cell patch-clamp techniques. Activation of wh
ole cell current with an outwardly rectifying current-potential relati
onship was observed in cells exposed to hyposmotic solutions. This cur
rent was determined, from the observed current-reversal potentials at
different Cl- concentrations, to be Cl- selective. The anion selectivi
ty sequence of the swelling-induced Cl- conductance was I- almost-equa
l-to NO3- almost-equal-to Br- > Cl- > 2-(N-morpholino)ethanesulfonic a
cid. The swelling-induced Cl- conductance was reversibly inhibited by
different Cl- channel blockers. Unlike diphenylamine-2-carboxylate or
5-nitro-2-(3-phenylpropylamino)-benzoate, which showed voltage-indepen
dent blockade, 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid showed
a marked voltage-dependent blockade of the volume-sensitive Cl- curre
nt, with a greater effect at depolarizing voltages. The swelling-induc
ed Cl- conductance appeared to be different from the Ca2+- or adenosin
e 3',5'-cyclic monophosphate-activated Cl- conductances on the basis o
f the following observations: 1) swelling-induced current activation w
as seen even in the presence of kinase inhibitor (H-8) or absence of e
xternal free Ca2+, and 2) further increase in current activation could
be produced by swelling after Ca2+-or adenosine 3',5'cyclic monophosp
hate-induced current activation. The swelling-induced Cl- conductance
may be involved in regulating epithelial cell volume as well as servin
g other important epididymal functions such as facilitating transepith
elial secretion of organic compounds.