The K-Cl cotransporter in the lobster stretch receptor neurone-a kinetic analysis.
(2002) In Journal of Theoretical Biology 217(3). p.287-309- Abstract
- Experiments were performed to define quantitatively the substrate (K(+) and Cl(-)) dependence of the transport function (production of equally large and oppositely directed K(+)and Cl(-) flows/currents) of an earlier (Theander et al., 1999) identified electroneutral K-Cl cotransporter in the slowly adapting stretch receptor neurone of the European lobster. The experiments were based on microelectrode techniques. This allowed us to perform steady-state measurements of the so-called "instantaneous" current-voltage relationships (around a holding voltage of -65 mV after a blockage of the cell's action potential and hyperpolarization-activated currents) and intracellular ion concentrations at various settings of the extracellular K(+) and... (More)
- Experiments were performed to define quantitatively the substrate (K(+) and Cl(-)) dependence of the transport function (production of equally large and oppositely directed K(+)and Cl(-) flows/currents) of an earlier (Theander et al., 1999) identified electroneutral K-Cl cotransporter in the slowly adapting stretch receptor neurone of the European lobster. The experiments were based on microelectrode techniques. This allowed us to perform steady-state measurements of the so-called "instantaneous" current-voltage relationships (around a holding voltage of -65 mV after a blockage of the cell's action potential and hyperpolarization-activated currents) and intracellular ion concentrations at various settings of the extracellular K(+) and Cl(-) concentrations. From the results, we could then define steady-state values of all of the cell's non-KCl cotransporter K(+) and Cl(-) currents. Finally, the negative sums of the inferred non-KCl cotransporter K(+) and Cl(-) currents could be taken as equivalents of the K-Cl cotransporter's K(+) and Cl(-) currents for the reason that, in steady state, all membrane currents add up to zero. For the cotransporter currents, thus inferred for a range from 2.5/410.5 to 40.0/448.0 mM external K(+)/Cl(-), we found that their absolute values increased in a nonlinear fashion from about 5 nA cell(-1) at the lowest, to about 20 nA cell(-1) at the highest external K(+)/Cl(-) concentrations. Formally, this relationship could be reproduced by a Hill function-based enzyme kinetic expression simulating inward and outward transmembrane electroneutral ion transports. Following insertion of this expression into a comprehensive model of electrical membrane functions and intracellular solute and solvent control in the lobster stretch receptor neurone, the model predictions suggested that the K-Cl cotransporter does play an important role in (a) keeping intracellular Cl(-) low for a proper function of the cell's inhibitory system, and (b) enabling rapid transmembrane K(+) shifts that provide for a stabilization of the cell's membrane voltage and membrane excitability in cases of varying extracellular K(+) concentrations. The model predictions gave, however, no clear evidence that the K-Cl cotransporter is critically involved in the cell's volume regulation in conditions of varying extracellular osmolalities. (Less)
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https://lup.lub.lu.se/record/110215
- author
- Fåhraeus, C LU ; Theander, S LU ; Edman, A and Grampp, Wolfgang LU
- organization
- publishing date
- 2002
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Experiments were performed to define quantitatively the substrate (K(+) and Cl(-)) dependence of the transport function (production of equally large and oppositely directed K(+)and Cl(-) flows/currents) of an earlier (Theander et al., 1999) identified electroneutral K-Cl cotransporter in the slowly adapting stretch receptor neurone of the European lobster. The experiments were based on microelectrode techniques. This allowed us to perform steady-state measurements of the so-called "instantaneous" current-voltage relationships (around a holding voltage of -65 mV after a blockage of the cell's action potential and hyperpolarization-activated currents) and intracellular ion concentrations at various settings of the extracellular K(+) and Cl(-) concentrations. From the results, we could then define steady-state values of all of the cell's non-KCl cotransporter K(+) and Cl(-) currents. Finally, the negative sums of the inferred non-KCl cotransporter K(+) and Cl(-) currents could be taken as equivalents of the K-Cl cotransporter's K(+) and Cl(-) currents for the reason that, in steady state, all membrane currents add up to zero. For the cotransporter currents, thus inferred for a range from 2.5/410.5 to 40.0/448.0 mM external K(+)/Cl(-), we found that their absolute values increased in a nonlinear fashion from about 5 nA cell(-1) at the lowest, to about 20 nA cell(-1) at the highest external K(+)/Cl(-) concentrations. Formally, this relationship could be reproduced by a Hill function-based enzyme kinetic expression simulating inward and outward transmembrane electroneutral ion transports. Following insertion of this expression into a comprehensive model of electrical membrane functions and intracellular solute and solvent control in the lobster stretch receptor neurone, the model predictions suggested that the K-Cl cotransporter does play an important role in (a) keeping intracellular Cl(-) low for a proper function of the cell's inhibitory system, and (b) enabling rapid transmembrane K(+) shifts that provide for a stabilization of the cell's membrane voltage and membrane excitability in cases of varying extracellular K(+) concentrations. The model predictions gave, however, no clear evidence that the K-Cl cotransporter is critically involved in the cell's volume regulation in conditions of varying extracellular osmolalities.
- in
- Journal of Theoretical Biology
- volume
- 217
- issue
- 3
- pages
- 287 - 309
- publisher
- Academic Press
- external identifiers
-
- wos:000179633800002
- pmid:12270275
- scopus:0036403090
- ISSN
- 1095-8541
- DOI
- 10.1006/jtbi.2002.3038
- language
- English
- LU publication?
- yes
- id
- 7a830409-abf5-4106-89a1-5b05befb4aed (old id 110215)
- alternative location
- http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12270275&dopt=Abstract
- date added to LUP
- 2016-04-01 16:01:03
- date last changed
- 2022-01-28 08:44:19
@article{7a830409-abf5-4106-89a1-5b05befb4aed,
abstract = {{Experiments were performed to define quantitatively the substrate (K(+) and Cl(-)) dependence of the transport function (production of equally large and oppositely directed K(+)and Cl(-) flows/currents) of an earlier (Theander et al., 1999) identified electroneutral K-Cl cotransporter in the slowly adapting stretch receptor neurone of the European lobster. The experiments were based on microelectrode techniques. This allowed us to perform steady-state measurements of the so-called "instantaneous" current-voltage relationships (around a holding voltage of -65 mV after a blockage of the cell's action potential and hyperpolarization-activated currents) and intracellular ion concentrations at various settings of the extracellular K(+) and Cl(-) concentrations. From the results, we could then define steady-state values of all of the cell's non-KCl cotransporter K(+) and Cl(-) currents. Finally, the negative sums of the inferred non-KCl cotransporter K(+) and Cl(-) currents could be taken as equivalents of the K-Cl cotransporter's K(+) and Cl(-) currents for the reason that, in steady state, all membrane currents add up to zero. For the cotransporter currents, thus inferred for a range from 2.5/410.5 to 40.0/448.0 mM external K(+)/Cl(-), we found that their absolute values increased in a nonlinear fashion from about 5 nA cell(-1) at the lowest, to about 20 nA cell(-1) at the highest external K(+)/Cl(-) concentrations. Formally, this relationship could be reproduced by a Hill function-based enzyme kinetic expression simulating inward and outward transmembrane electroneutral ion transports. Following insertion of this expression into a comprehensive model of electrical membrane functions and intracellular solute and solvent control in the lobster stretch receptor neurone, the model predictions suggested that the K-Cl cotransporter does play an important role in (a) keeping intracellular Cl(-) low for a proper function of the cell's inhibitory system, and (b) enabling rapid transmembrane K(+) shifts that provide for a stabilization of the cell's membrane voltage and membrane excitability in cases of varying extracellular K(+) concentrations. The model predictions gave, however, no clear evidence that the K-Cl cotransporter is critically involved in the cell's volume regulation in conditions of varying extracellular osmolalities.}},
author = {{Fåhraeus, C and Theander, S and Edman, A and Grampp, Wolfgang}},
issn = {{1095-8541}},
keywords = {{Experiments were performed to define quantitatively the substrate (K(+) and Cl(-)) dependence of the transport function (production of equally large and oppositely directed K(+)and Cl(-) flows/currents) of an earlier (Theander et al.; 1999) identified electroneutral K-Cl cotransporter in the slowly adapting stretch receptor neurone of the European lobster. The experiments were based on microelectrode techniques. This allowed us to perform steady-state measurements of the so-called "instantaneous" current-voltage relationships (around a holding voltage of -65 mV after a blockage of the cell's action potential and hyperpolarization-activated currents) and intracellular ion concentrations at various settings of the extracellular K(+) and Cl(-) concentrations. From the results; we could then define steady-state values of all of the cell's non-KCl cotransporter K(+) and Cl(-) currents. Finally; the negative sums of the inferred non-KCl cotransporter K(+) and Cl(-) currents could be taken as equivalents of the K-Cl cotransporter's K(+) and Cl(-) currents for the reason that; in steady state; all membrane currents add up to zero. For the cotransporter currents; thus inferred for a range from 2.5/410.5 to 40.0/448.0 mM external K(+)/Cl(-); we found that their absolute values increased in a nonlinear fashion from about 5 nA cell(-1) at the lowest; to about 20 nA cell(-1) at the highest external K(+)/Cl(-) concentrations. Formally; this relationship could be reproduced by a Hill function-based enzyme kinetic expression simulating inward and outward transmembrane electroneutral ion transports. Following insertion of this expression into a comprehensive model of electrical membrane functions and intracellular solute and solvent control in the lobster stretch receptor neurone; the model predictions suggested that the K-Cl cotransporter does play an important role in (a) keeping intracellular Cl(-) low for a proper function of the cell's inhibitory system; and (b) enabling rapid transmembrane K(+) shifts that provide for a stabilization of the cell's membrane voltage and membrane excitability in cases of varying extracellular K(+) concentrations. The model predictions gave; however; no clear evidence that the K-Cl cotransporter is critically involved in the cell's volume regulation in conditions of varying extracellular osmolalities.}},
language = {{eng}},
number = {{3}},
pages = {{287--309}},
publisher = {{Academic Press}},
series = {{Journal of Theoretical Biology}},
title = {{The K-Cl cotransporter in the lobster stretch receptor neurone-a kinetic analysis.}},
url = {{http://dx.doi.org/10.1006/jtbi.2002.3038}},
doi = {{10.1006/jtbi.2002.3038}},
volume = {{217}},
year = {{2002}},
}