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Two distinct K(+)-ATPase activities in rabbit distal colon
S I Abrahamse1, H R De Jonge, R J Bindels
1Department of Cell Physiology, University of Nijmegen, The Netherlands.
Biochemical and Biophysical Research Communications
|February 27, 1995
Summary
Rabbit colon cells contain two distinct types of potassium-stimulated ATPase (K(+)-ATPase). This finding, observed in both surface and crypt cells, reveals a more complex cellular machinery than previously understood.
Area of Science:
- Cell Biology
- Gastroenterology
- Physiology
Background:
- The distal colon's epithelial cells are crucial for ion transport.
- Understanding the specific enzymes involved in this transport is essential for comprehending colon function.
Purpose of the Study:
- To investigate the distribution and characteristics of K(+)-ATPase activity in rabbit distal colon surface and crypt cells.
- To determine if distinct K(+)-ATPase isoforms are present in these cell types.
Main Methods:
- Cell separation of surface and crypt epithelial cells from rabbit distal colon.
- Validation of cell separation using P-glycoprotein expression via Western blot analysis.
- Assay of K(+)-stimulated ouabain-insensitive ATPase activity and its inhibition by SCH 28080.
Main Results:
- P-glycoprotein, a marker for differentiated surface cells, showed a 6-fold higher expression in surface cells.
- K(+)-ATPase activity was detected in both surface and crypt cells.
- Surface cell K(+)-ATPase activity was only partially inhibited by SCH 28080, whereas crypt cell activity was fully sensitive to SCH 28080.
Conclusions:
- The differential inhibition of K(+)-ATPase activity by SCH 28080 suggests the presence of at least two distinct K(+)-ATPases in rabbit colonic epithelial cells.
- These findings highlight a previously unrecognized complexity in the enzymatic machinery of the colon epithelium.