ISSN:
1432-2013
Keywords:
Human sweat ducts
;
Cell culture
;
Electrophysiology
;
Cl− conductances
;
K+ conductances
;
Isoproterenol
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract The purpose of this study was to characterize the ion conductances, in particular those for Cl− and K+, of human sweat duct cells grown in primary culture. Sweat duct cells from healthy individuals were grown to confluence on a dialysis membrane, which was then mounted in a mini-Ussing chamber and transepithelial and intracellular potentials were measured under open-circuit conditions. Under control conditions the epithelia developed mucosa-negative transepithelial potentials, V te, of about −10mV. The apical membrane potential, V a, was −25 mV to −30 mV (n=97) in most cells, but several cells had a higher potential of about −55 mV (n=29). Mucosal amiloride (10 μmol/l) hyperpolarized V a from −31±1 mV to a new sustained level of −46±2 mV (n=36). These changes were accompanied by increase in the fractional resistance of the apical membrane, fR a, and decreases of V te and the equivalent short-circuit current, I sc. In amiloride-treated tissues an increase in mucosal K+ concentration (5 mmol/l to 25 mmol/l) depolarized V a by 5±1 mV (n=8), while the same step on the serosal side depolarized V a by 20±2 mV (n=8). A Cl− channel blocker 3′,5-dichloro-diphenylamine-2-carboxylate DCl-DPC; 10 μmol/l) depolarized V a by 5±1 mV (n=6), an effect that was lost after amiloride application. The blocker had no effect from the serosal side. Reduction of mucosal Cl− (from 120 to 30 or 10 mmol/l) depolarized V a by 9–11 mV (n=35), an effect that was often followed by a secondary hyperpolarization of 10–30 mV (n=27). Isoproterenol (5 μmol/l) increased the V a responses to low Cl− such that the depolarizing response was increased from 10±1 mV to 19±2 mV (n=8); the hyperpolarizing response seemed to be reduced. With changes in Cl− concentration on the serosal side, V a remained relatively constant at −25 mV, while V te decreased from −8 mV to−3 mV; hence, V bl depolarized by about 5 mV. Taken together, our results show that the human sweat duct epithelium possesses Na+, K+ and Cl− conductances on the luminal membrane and Cl− and K+ conductances on the basolateral membrane. The Cl− conductances on the luminal membrane is sensitive to DCl-DPC, and can be activated by isoproterenol. The small K+ conductance on the luminal membrane could account for some K+ secretion in sweat glands.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00370414
Permalink
