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Intracellular potassium activity and the role of potassium in transepithelial salt transport in the human reabsorptive sweat duct
- Source :
- The Journal of membrane biology. 119(3)
- Publication Year :
- 1991
-
Abstract
- We have measured the intracellular potassium activity, [K+]i and the mechanisms of transcellular K+ transport in reabsorptive sweat duct (RSD) using intracellular ion-sensitive microelectrodes (ISMEs). The mean value of [K+]i in RSD is 79.8 +/- 4.1 mM (n = 39). Under conditions of microperfusion, the [K+]i is above equilibrium across both the basolateral membrane, BLM (5.5 times) and the apical membrane, APM (7.8 times). The Na+/K+ pump inhibitor ouabain reduced [K+]i is insensitive to the Na+/K+/2 Cl- cotransport inhibitor bumetanide in the bath. Cl- substitution in the lumen had no effect on [K+]i. In contrast, Cl- substitution in the bath (basolateral side) depolarized BLM from -26.0 +/- 2.6 mV to -4.7* +/- 2.4 mV (n = 3; *indicates significant difference) and decreased [K+]i from 76.0 +/- 15.2 mM to 57.7* +/- 12.7 mM (n = 3). Removal of K+ in the bath decreased [K+]i from 76.3 +/- 15.0 mM to 32.3 +/- 7.6 mM (n = 4) while depolarizing the BLM from -32.5 +/- 4.1 mV to -28.3* +/- 3.0 mV (n = 4). Raising the [K+] in the bath by 10-fold increased [K+]i from 81.7 +/- 9.0 mM to 95.0* +/- 13.5 mM and depolarized the BLM from -25.7 +/- 2.4 mV to -21.3* +/- 2.9 mV (n = 4). The K+ conductance inhibitor, Ba2+, in the bath also increased [K+]i from 85.8 +/- 6.7 mM to 107.0* +/- 11.5 mM (n = 4) and depolarized BLM from -25.8 +/- 2.2 mV to -17.0* +/- 3.1 mV (n = 4). Amiloride at 10(-6) M increased [K+]i from 77.5 +/- 18.8 mM to 98.8* +/- 21.6 mM (n = 4) and hyperpolarized both the BLM (from -27.5 +/- 1.4 mV to -46.0* +/- 3.5 mV, n = 4). However, amiloride at 10(-4) M decreased [K+]i from 64.5 +/- 0.9 mM to 36.0* +/- 9.9 mM and hyperpolarized both the BLM (from -24.7 +/- 1.4 mV to -43.5* +/- 4.2 mV) and APM (from -18.3 +/- 0.9 mV to -43.5* +/- 4.2 mV, n = 6). In contrast to the observations at the BLM, substitution of K+ or application of Ba2+ in the lumen had no effect on the [K+]i or the electrical properties of RSD, indicating the absence of a K+ conductance in the APM.(ABSTRACT TRUNCATED AT 400 WORDS)
- Subjects :
- medicine.medical_specialty
Conductometry
Physiology
Biophysics
Analytical chemistry
Biological Transport, Active
In Vitro Techniques
Ouabain
Epithelium
Amiloride
Internal medicine
medicine
Humans
Ion transporter
Membrane potential
Reabsorption
Chemistry
Cell Membrane
Sodium
Electric Conductivity
Cell Biology
Apical membrane
Sweat Glands
Endocrinology
Barium
Potassium
Cotransporter
Microelectrodes
Bumetanide
medicine.drug
Subjects
Details
- ISSN :
- 00222631
- Volume :
- 119
- Issue :
- 3
- Database :
- OpenAIRE
- Journal :
- The Journal of membrane biology
- Accession number :
- edsair.doi.dedup.....b6b57a6f3b7e4c13080af5438e170c21