Evidence for a K/sup +/-H/sup +/ exchanger in rabbit renal cortical brush-border membrane vesicles
An outward-directed H/sup +/ gradient stimulated /sup 86/Rb/sup +/ uptake in brush-border membrane vesicles isolated from rabbit renal cortex. This H/sup +/ gradient-stimulated /sup 86/Rb/sup +/ uptake was inhibited by unlabeled K/sup +/ (IC/sub 50/ = 7.5 mM). The carrier system responsible for this uptake is different from the Na/sup +/-H/sup +/ exchanger, because inhibitors of the Na/sup +/-H/sup +/ exchanger did not affect or affected minimally the /sup 86/Rb/sup +/ uptake whereas these compounds caused 60-85% inhibition of the /sup 22/Na/sup +/ uptake. Moreover, /sup 86/Rb/sup +/ uptake was preferentially inhibited by unlabeled K/sup +/ and Rb/sup +/ whereas /sup 22/Na/sup +/ uptake was preferentially inhibited by Na/sup +/ and Li/sup +/. Furosemide, an inhibitor of the Na/sup +/-K/sup +/-2Cl/sup -/ cotransporter and Ca/sup 2 +/ and Ba/sup 2 +/, modulators of the K/sup +/-channel did not affect /sup 86/Rb uptake in the renal brush-border membrane vesicles, indicating that these transport mechanisms were also not responsible for the observed /sup 86/Rb/sup +/ uptake. These results provide evidence for the presence of a distinct K/sup +/-H/sup +/ exchanger in renal cortical brush-border membrane vesicles.
- Research Organization:
- Medical College of Georgia, Augusta (USA)
- OSTI ID:
- 5409542
- Journal Information:
- Ga. J. Sci.; (United States), Vol. 45:2
- Country of Publication:
- United States
- Language:
- English
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550201* - Biochemistry- Tracer Techniques