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Potassium currents of isolated Necturus enterocytes: a whole-cell patch-clamp study
D N Sheppard1, M A Valverde, F Giraldez
1AFRC Institute of Animal Physiology and Genetics Research, Babraham, Cambridge.
The Journal of Physiology
|February 1, 1991
Summary
This study reveals calcium-activated potassium (K+) currents in Necturus maculosus enterocytes. These currents are crucial for intestinal ion transport and are modulated by intracellular calcium levels.
Area of Science:
- Cellular physiology
- Ion channel biophysics
- Epithelial transport
Background:
- Enterocytes play a vital role in intestinal absorption and secretion.
- Understanding ion transport mechanisms is key to comprehending epithelial function.
Purpose of the Study:
- To investigate the ionic currents present in isolated Necturus maculosus enterocytes.
- To characterize the properties and ionic basis of outwardly rectifying currents.
Main Methods:
- Whole-cell patch-clamp recordings were performed on isolated enterocytes.
- Intracellular and extracellular solutions were manipulated to study ion selectivity.
- K+ channel inhibitors (Ba2+, TEA) were used to identify the charge carrier.
Main Results:
- A strongly outwardly rectifying current was observed, dependent on intracellular K+ and Ca2+.
- Current activation kinetics showed voltage dependence, with faster rates at depolarized potentials.
- Maxi K+ channels and lower conductance K+ channels were identified in outside-out patches.
Conclusions:
- The observed currents are primarily carried by K+ ions, likely through maxi K+ channels.
- Intracellular calcium concentration significantly modulates the magnitude and activation kinetics of these currents.
- These findings contribute to understanding K+ transport in intestinal epithelial cells.