cAMP-associated inhibition of Na/sup +/-H/sup +/ exchanger in rabbit kidney brush-border membranes
Adenosine 3',5'-cyclic monophosphate (cAMP) inhibits the rate of bicarbonate reabsorption and the rate of Na/sup +/-H/sup +/ exchange transport in the apical membrane of the proximal convoluted tubule. To study the relation between cAMP, cAMP-dependent protein kinase, and Na/sup +/-H/sup +/ exchange transport, brush-border membrane vesicles from the rabbit kidney were phosphorylated in vitro. The rate of proton gradient-stimulated amiloride-inhibitable /sup 22/Na/sup +/ uptake was measured as an index of Na/sup +/-H/sup +/ exchange transport activity. The inclusion of cAMP (10/sup -6/ M) in a phosphorylating solution containing ATP decreased the 10-s uptake of amiloride-sensitive sodium from 2.25 +/-0.21 nmol/mg protein in controls to 1.94 +/- 0.19. Incubation of vesicles in the presence of purified catalytic subunit of cAMP-dependent protein kinase inhibited the amiloride-sensitive uptake of /sup 22/Na/sup +/ at 10. The inhibitory effect of both cAMP and catalytic subunit of cAMP-dependent protein kinase was blocked by the specific thermostable protein inhibitor of the kinase. These studies demonstrate that activation of endogenous membrane-bound cAMP-dependent protein kinase or exposure to exogenous catalytic subunit of cAMP-dependent protein kinase inhibits the rate of Na/sup +/-H/sup +/ exchange transport in the brush-border membrane of the rabbit kidney.
- Research Organization:
- Univ. of Texas Medical School, Houston
- OSTI ID:
- 6409533
- Journal Information:
- Am. J. Physiol.; (United States), Vol. 252:1
- Country of Publication:
- United States
- Language:
- English
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551001* - Physiological Systems- Tracer Techniques