Related Experiment Videos
Pathways for volume flow and volume regulation in leaky epithelia
Pflugers Archiv : European Journal of Physiology
|January 1, 1985
Summary
Water transport across kidney tubules primarily uses continuous pathways through cell membranes. This is supported by evidence of high water permeability, low activation energy, and inhibition by pCMBS, suggesting specific protein channels are involved.
Area of Science:
- Cellular Physiology
- Renal Physiology
- Membrane Transport
Background:
- Understanding water movement across proximal straight tubular cells is crucial for comprehending kidney function and osmotic equilibration.
- The basolateral plasma membrane's role in water permeability (Poscb) and its characteristics are key to this process.
Purpose of the Study:
- To investigate the mechanisms and pathways of water transport across proximal straight tubular cells.
- To determine the contribution of transcellular versus paracellular routes to overall water permeability in leaky epithelia.
Main Methods:
- Measurement of the water osmotic permeability coefficient (Poscb) of the basolateral plasma membrane.
- Assessment of the effect of pCMBS on Poscb and activation energy (Ea).
- Utilizing Nuclear Magnetic Resonance (NMR) to measure the water diffusive permeability coefficient (Pd).
- Analyzing solute drag and comparing transcellular versus transepithelial water permeability coefficients.
Main Results:
- Poscb is high, exhibits activation energy similar to free water movement, and is inhibited by pCMBS, indicating involvement of water channels.
- Preliminary NMR data suggest a Poscb/Pd ratio near 4-5.
- Evidence of significant paracellular water flow in leaky epithelia, demonstrated by solute drag and lower transcellular permeability compared to transepithelial values.
Conclusions:
- Continuous pathways, likely protein channels, facilitate water movement across the cell membrane during osmotic equilibration.
- A significant paracellular water flow component is necessary to explain the observed transepithelial water permeability in leaky epithelia.