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Interaction between the basolateral K+ and apical Na+ conductances in Necturus urinary bladder.
The Journal of General Physiology
|April 1, 1987
Summary
Blocking basolateral potassium channels in Necturus urinary bladders reduces sodium transport by decreasing both potassium exit and sodium entry. This highlights feedback mechanisms maintaining cellular balance during transport changes.
Area of Science:
- Physiology
- Cell Biology
- Membrane Transport
Background:
- Epithelial transport involves coordinated ion conductances.
- Previous studies showed apical/basolateral pump changes affect basolateral K+ conductance.
Purpose of the Study:
- Investigate if modulating basolateral K+ conductance affects apical Na+ conductance and Na+-K+ pump activity.
- Determine the role of basolateral K+ channels in regulating epithelial sodium transport.
Main Methods:
- Used Necturus urinary bladders, impaled with microelectrodes.
- Rapidly changed serosal solutions and applied K+ channel blockers (Ba2+, Cs+, Rb+).
- Measured electrical resistance (apical Ra, basolateral Rb) and cell membrane potentials.
Main Results:
- K+ channel blockers increased basolateral resistance (>75%).
- This was accompanied by increased apical resistance (>20%) and decreased Na+ transport.
- Apical resistance changes were not due to membrane potential nonlinearities.
Conclusions:
- Blocking basolateral K+ conductance reduces Na+ transport by limiting K+ exit and Na+ entry.
- Feedback relationships between apical and basolateral conductances maintain cellular homeostasis.
- These findings reveal a network regulating transport during physiological changes.