These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Regulation of the renal Na-HCO3 cotransporter by cAMP and Ca-dependent protein kinases.
    Author: Ruiz OS, Arruda JA.
    Journal: Am J Physiol; 1992 Apr; 262(4 Pt 2):F560-5. PubMed ID: 1314505.
    Abstract:
    Changes in the activity of the brush-border Na-H antiporter are accompanied by parallel changes in the activity of the Na-HCO3 cotransporter. Adenosine 3',5'-cyclic monophosphate (cAMP) and calmodulin inhibit the Na-H antiporter, whereas protein kinase C (PKC) stimulates it. We hypothesized that cAMP, calmodulin, and PKC should have similar effects on the Na-HCO3 cotransporter activity. Phosphorylated renal basolateral membranes were treated with either cAMP, calmodulin, or phorbol ester. cAMP, 1 microM, inhibited HCO3-dependent 22Na uptake without affecting 22Na uptake in presence of gluconate, suggesting that cAMP inhibits Na-HCO3 cotransporter activity without altering diffusive 22Na uptake. The effect of cAMP to inhibit the Na-HCO3 cotransporter could also be elicited by the catalytic subunit of cAMP, and this inhibitory effect was prevented by the protein kinase A (PKA) inhibitor. Calmodulin (1 microM), in presence of Ca, also inhibited HCO3-dependent 22Na uptake in presence of HCO3, whereas 22Na uptake in the presence of gluconate was unchanged. The inhibitory effect of calmodulin on HCO3-dependent 22Na uptake was prevented by N-(4-aminobutyl)-5-chloro-2-naphthalene sulfonamide (W-13), an inhibitor of calmodulin. Phorbol 12-myristate 13-acetate and PKC stimulated Na-HCO3 cotransporter activity, whereas the inactive analogue, 4 alpha-phorbol, failed to elicit such a stimulation. Basolateral membranes displayed cAMP-dependent and Ca-dependent protein kinase activities. Thus PKA and Ca-dependent protein kinases regulate the activity of the Na-HCO3 cotransporter and suggest that hormones that act through these systems modulate the activity of the Na-HCO3 cotransporter.
    [Abstract] [Full Text] [Related] [New Search]