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Localization and regulation of acid-base secretory currents from individual epithelial cells
C Scheffey1, A M Shipley, J H Durham
1Department of Biological Sciences, Columbia University, New York, New York 10027.
The American Journal of Physiology
|December 1, 1991
Summary
Turtle bladders have distinct cells for acid and alkali excretion. Researchers measured electrical currents to show separate cell types manage these processes, revealing how the bladder regulates acid-base balance.
Area of Science:
- Physiology
- Urology
- Cell Biology
Background:
- The turtle urinary bladder exhibits diverse epithelial cell types.
- These cells are hypothesized to independently manage electrogenic acid and alkali excretion.
- Understanding these mechanisms is crucial for comprehending renal acid-base homeostasis.
Purpose of the Study:
- To investigate the specific cell types responsible for acid and alkali excretion in the turtle urinary bladder.
- To measure and localize the electrical currents associated with these transport functions.
- To determine if acid and alkali secretion can occur simultaneously in distinct cell populations.
Main Methods:
- Utilized a two-dimensional vibrating probe to scan the luminal surface of the turtle urinary bladder.
- Measured electrical currents produced by individual epithelial cells.
- Stimulated alkali secretion using adenosine 3',5'-cyclic monophosphate and manipulated luminal pH to differentiate transport functions.
Main Results:
- Acidification (outward current) was localized to carbonic anhydrase-rich cells (CA cells), accounting for total acidification.
- Alkali secretion (inward current) was observed in a subset of cells under specific conditions, but not consistently across all bladders.
- Demonstrated that acid and alkali transport functions can occur simultaneously in separate cell populations within the bladder epithelium.
Conclusions:
- Specific epithelial cell types, including CA cells, are responsible for distinct acid and alkali excretion.
- The turtle urinary bladder possesses the capability for simultaneous, localized acid and alkali secretion.
- Net acid-base balance is regulated by controlling the transport rates of these specialized, separate cells.
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