Ca2+-activated Cl- channel currents in rat ventral prostate epithelial cells.
BACKGROUND
In many epithelial tissues, the Cl(-) efflux via Ca(2+)-activated Cl(-) channels (Cl(Ca)) play a key role for the fluid secretion. To elucidate the mechanism of prostatic fluid secretion, the properties of whole-cell chloride conductance were investigated.


METHODS
Rat prostate secretory epithelial cells (RPSECs) were isolated by collagenase treatment, and were used for the whole-cell voltage clamp. Both extra- and intracellular monovalent cations were replaced by N-methyl-D-glucamate to record the Cl(-) current selectively.


RESULTS
A bath application of Ca(2+)-ionophore, ionomycin (0.2 micro M), increased the membrane conductance with outwardly rectifying voltage-dependence. On step-like depolarization from -60 to +80 mV (500 msec), the ionomycin-induced current showed slowly activating kinetics, a known property of Cl(Ca) current (I(Cl(Ca))) of other tissues. The relative permeability of Cl(Ca) to various anions was calculated from the reversal potentials measured under a total replacement of extracellular Cl(-) with various anions, and the relative order of permeability was SCN(-)>I(-)>Br(-)>Cl(-)>>gluconate. The amplitude of I(Cl(Ca)) was decreased by various anion channel blockers: niflumic acid (100 micro M), DPC (100 micro M), DIDS (1 mM), and NPPB (200 micro M).


CONCLUSIONS
RPSECs have Cl(Ca) that may provide Cl(-) efflux pathways for the exocrine secretions of the prostate.
Kim
Sung Joon
SJ
Department of Physiology, Sungkyunkwan University School of Medicine, Suwon, Korea. sjoonkim@med.skku.ac.kr
Shin
Sun Young
SY
Lee
Ji Eun
JE
Kim
Jun Hee
JH
Uhm
Dae-Yong
DY
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000818:Animals; D000838:Anions / Q000378:metabolism; D002118:Calcium / Q000502:physiology*; D018118:Chloride Channels / Q000037:antagonists & inhibitors / Q000502:physiology*; D004553:Electric Conductivity; D004847:Epithelial Cells / Q000378:metabolism; D015759:Ionomycin / Q000494:pharmacology; D007476:Ionophores / Q000494:pharmacology; D008297:Male; D009544:Niflumic Acid / Q000494:pharmacology; D009579:Nitrobenzoates / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D010539:Permeability; D011467:Prostate / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D062367:ortho-Aminobenzoates / Q000494:pharmacology
D000838:Anions; D018118:Chloride Channels; D007476:Ionophores; D009579:Nitrobenzoates; D062367:ortho-Aminobenzoates; C058176:5-nitro-2-(3-phenylpropylamino)benzoic acid; D009544:Niflumic Acid; D015759:Ionomycin; C001209:fenamic acid; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D002118:Calcium