H(+)-K(+)-ATPase activity in rat collecting duct segments
J D Gifford1, L Rome, J H Galla
1Department of Medicine, University of Cincinnati, Ohio 45267-0585.
The American Journal of Physiology
|April 1, 1992
Summary
The H(+)-K(+)-ATPase significantly impacts carbon dioxide transport in rat kidneys. This enzyme is crucial for absorption in the outer and inner medullary collecting ducts and secretion in the cortical collecting duct.
Area of Science:
- Nephrology
- Renal Physiology
- Cellular Biology
Background:
- Previous research indicated H(+)-K(+)-ATPase presence in rat kidney intercalated cells.
- This enzyme shares properties with the gastric proton pump.
Purpose of the Study:
- To investigate the functional role of H(+)-K(+)-adenosinetriphosphatase (ATPase) in regulating total carbon dioxide (tCO2) transport.
- To determine the enzyme's contribution along the rat collecting duct.
Main Methods:
- Isolated perfused rat collecting duct segments were used.
- Baseline tCO2 transport was measured.
- The H(+)-K(+)-ATPase inhibitor, Sch 28080, was applied to perfusate or bath.
Main Results:
- Sch 28080 significantly reduced tCO2 absorption in the outer medullary (OMCD) and initial inner medullary collecting duct (IMCD1).
- No effect on tCO2 transport was observed in the cortical collecting duct (CCD) when Sch 28080 was in the perfusate.
- In rats with acute alkalosis, Sch 28080 in the bath inhibited tCO2 secretion in the CCD.
Conclusions:
- H(+)-K(+)-ATPase plays a key role in tCO2 absorption (OMCD, IMCD1) and secretion (CCD).
- Functional differences exist between HCO3(-)-absorbing intercalated cells in the cortex and medulla.
- The study highlights the enzyme's importance in distal acidification under various acid-base conditions.
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