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: Protein kinase C activation has dissimilar effects on sodium-coupled uptakes in renal proximal tubular cells in primary culture.
    Author: Friedlander G, Amiel C.
    Journal: J Biol Chem; 1989 Mar 05; 264(7):3935-41. PubMed ID: 2537298.
    Abstract:
    Protein kinase C (Ca2+/phospholipid-dependent enzyme) was shown to be present in renal brush border membranes. To evaluate the influence of protein kinase C activation on three apical transport systems, we studied the effect of phorbol myristate acetate (PMA) and of two diacylglycerol analogs, oleoylacetylglycerol and dioctanoylglycerol, on sodium-dependent uptakes of phosphate (Pi), L-alanine, and alpha-methyl-D-glucopyranoside (MGP), as well as on specific phlorizin binding, in cultured rabbit proximal tubular cells. PMA, at 100 ng/ml, decreased the Vmax of Pi and MGP uptake by 30 and 17%, respectively, but not that of alanine uptake. None of the Km values were affected. PMA also decreased the number of phlorizin binding sites by 40%. PMA-induced inhibition of Pi and MGP uptake was time- and concentration-dependent, was mimicked by oleoylacetylglycerol, dioctanoylglycerol, and the diacylglycerol kinase inhibitor R59022, and was reversed by the protein kinase C antagonist 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H7). The effects of PMA persisted in the presence of amiloride and dimethyl amiloride, and were potentiated by Ca2+ ionophore A23187. Opening of tight junctions blunted subsequent PMA-induced decrease of MGP uptake, but not of Pi uptake. It is concluded that: (i) activation of protein kinase C does not affect similarly Na-Pi, Na-hexose, and Na-alanine cotransport; and (ii) different pathways are likely to be involved in the observed effects.
    [Abstract] [Full Text] [Related] [New Search]