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. MATERIALS AND 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. Copyright 2003 Wiley-Liss, Inc.
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. MATERIALS AND 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. Copyright 2003 Wiley-Liss, Inc.
Authors: Kim A Davis; Sue E Samson; Kelly Best; Kanwaldeep K Mallhi; Magdalena Szewczyk; John X Wilson; Chiu-Yin Kwan; Ashok K Grover Journal: Br J Pharmacol Date: 2006-01 Impact factor: 8.739