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Background chloride currents in fetal human nasopharyngeal epithelial cells

Sun Xuerong, Wang Liwei, Mao Jianwen, Zhu Linyan, Nie Sihuai, Zhong Ping, Chen Lixin

Laboratory of Physiology

Abstract

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 #mu#mol/L) and 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB) (100 #mu#mol/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.

Key words: Epithelial cells;Background currents;Chloride channels

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Citing This Article：

Sun Xuerong, Wang Liwei, Mao Jianwen, Zhu Linyan, Nie Sihuai, Zhong Ping, Chen Lixin. Background chloride currents in fetal human nasopharyngeal epithelial cells. Acta Physiol Sin 2005; 57 (3): (in Chinese with English abstract).