cAMP-associated inhibition of Na+-H+ exchanger in rabbit kidney brush-border membranes

Am J Physiol. 1987 Jan;252(1 Pt 2):F19-25. doi: 10.1152/ajprenal.1987.252.1.F19.

Abstract

Adenosine 3',5'-cyclic monophosphate (cAMP) inhibits the rate of bicarbonate reabsorption and the rate of Na+-H+ exchange transport in the apical membrane of the proximal convoluted tubule. To study the relation between cAMP, cAMP-dependent protein kinase, and Na+-H+ exchange transport, brush-border membrane vesicles from the rabbit kidney were phosphorylated in vitro. The rate of proton gradient-stimulated amiloride-inhibitable 22Na+ uptake was measured as an index of Na+-H+ exchange transport activity. The inclusion of cAMP (10(-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 (P less than 0.001). Incubation of vesicles in the presence of purified catalytic subunit of cAMP-dependent protein kinase inhibited the amiloride-sensitive uptake of 22Na+ at 10 s from 2.35 +/- 0.49 nmol/mg protein to 2.05 +/- 0.44 (P less than 0.005). 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+-H+ exchange transport in the brush-border membrane of the rabbit kidney.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Amiloride / pharmacology
  • Animals
  • Carrier Proteins / antagonists & inhibitors*
  • Cyclic AMP / pharmacology*
  • Female
  • Kidney Cortex / metabolism*
  • Kidney Tubules, Proximal / metabolism
  • Kinetics
  • Microvilli / drug effects
  • Microvilli / metabolism*
  • Phosphorylation
  • Protein Kinases / metabolism*
  • Rabbits
  • Sodium-Hydrogen Exchangers

Substances

  • Carrier Proteins
  • Sodium-Hydrogen Exchangers
  • Amiloride
  • Adenosine Triphosphate
  • Cyclic AMP
  • Protein Kinases