[Background chloride currents in fetal human nasopharyngeal epithelial cells].
To characterize the background current in fetal human nasopharyngeal epithelial cells and clarify its relationship with volume activated Cl(-) currents (I(Cl,vol)), whole-cell patch clamp and cell imaging techniques were employed. Under isotonic conditions, a background current [(5.9+/-2.1) pA/pF at +80 mV, n=21] was detected. The current presented a weak outward rectification and a negligible time-dependent inactivation. The current-voltage relationship showed that the reversal potential of the background current [(-0.73+/-1.7) mV, n=21] was close to the calculated equilibrium potential for Cl(-)(-0.9 mV). Application of extracellular hypertonic stimulation (440 mOsmol/L) suppressed the current by (59.6+/-7.1)% and the inhibition was reversible after returned to isotonic conditions. Bathing the cells in hypotonic solution (160 mOsmol/L) induced a volume-sensitive Cl(-) current. The Cl(-) channel blockers, tamoxifen (20 micromol/L) and 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB) (100 micromol/L), inhibited the background current by (74.0+/-5.2)% (P<0.01, n=5) and (60.9+/-8.9)% (P<0.01, n=6) at +80 mV and increased basal cell volume by (107.7+/-2.9)% (P<0.01, n=25) and (104.4+/-2.4)% (P<0.01, n=19), respectively. The data indicate that Cl(-) current is an important component of the background current in fetal human nasopharyngeal epithelial cells. The background Cl(-) current is involved in volume activated Cl(-) current and basal cell volume regulation.
Sun
Xue-Rong
XR
Laboratory of Physiology, Guangdong Medical College, Zhanjiang 524023, China.
Wang
Li-Wei
LW
Mao
Jian-Wen
JW
Zhu
Lin-Yan
LY
Nie
Si-Huai
SH
Zhong
Ping
P
Chen
Li-Xin
LX
D002478:Cells, Cultured; D018118:Chloride Channels / Q000037:antagonists & inhibitors / Q000502:physiology*; D004594:Electrophysiology; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D005333:Fetus; D006801:Humans; D009305:Nasopharynx / Q000166:cytology*; D009579:Nitrobenzoates / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D013629:Tamoxifen / Q000494:pharmacology
D018118:Chloride Channels; D009579:Nitrobenzoates; D013629:Tamoxifen; C058176:5-nitro-2-(3-phenylpropylamino)benzoic acid