| Autor: |
Attmane-Elakeb, Amel, Boulanger, Henry, Vernimmen, Catherine, Bichara, Maurice |
| Zdroj: |
Journal of Biological Chemistry; October 1997, Vol. 272 Issue: 41 p25668-25677, 10p |
| Abstrakt: |
To characterize and localize a K+/H+antiport mechanism in the renal medullary thick ascending limb (MTAL), membrane vesicles were isolated from a rat MTAL homogenate. K+/H+antiport (in > out H+gradient-stimulated86Rb+uptake) was abolished by barium and verapamil (apparent Kiof 55 μm) but unaffected by other K+channel blockers such as quinidine and high amiloride concentrations. SCH 28080, a H+/K+-ATPase blocker, did not affect K+/H+antiport. K+/H+antiport activity was correlated positively with the enrichment factor of the membranes in the apical marker enzyme alkaline phosphatase (r= 0.875, p< 0.01) and negatively correlated with the enrichment factor in basolateral Na+/K+-ATPase (r= −0.665,p< 0.05). Moreover, a functional interaction occurred with Na+/H+exchange (NHE) consistent with colocation of K+/H+antiport and apical NHE-3, not basolateral NHE-1. K+/H+antiport was shown by intracellular pH measurements to be inhibited by arginine vasopressin and 8-bromo-cAMP through cAMP-dependent protein kinase (protein kinase A) activation. These results demonstrate the presence of a K+/H+antiport mechanism, which is inhibited by arginine vasopressin via protein kinase A, in the apical membrane of the MTAL. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
|
