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: [3H]bumetanide binding and inhibition of Na+ + K+ + Cl- co-transport: demonstration of specificity by the use of MDCK cells deficient in co-transport activity.
    Author: Popowicz P, Simmons NL.
    Journal: Q J Exp Physiol; 1988 Mar; 73(2):193-202. PubMed ID: 3380935.
    Abstract:
    Cultured renal MDCK cells possess a Na+ + K+ + Cl- co-transport system which is inhibited with high affinity by loop diuretics (K0.5 for bumetanide inhibition = 0.28 microM). By the use of 'mutant' cell lines deficient in co-transport flux the specific interaction of [3H]bumetanide with the co-transporter has been identified. [3H]Bumetanide uptake in parental MDCK-N cells in the range 0-1 microM comprises a non-saturable linear component, assessed by the inclusion of 100 microM-unlabelled bumetanide and a saturable component (K0.5 = 0.19 microM and Bmax = 0.55 pmol/10(6) cells). Though the magnitude of the linear non-specific component was little different between the parental MDCK-N cell line and two co-transport-deficient mutant cell lines (LKC1 and LKA3), the magnitude of the saturable component was markedly reduced in both co-transport-deficient mutants. In addition to the saturable component associated with flux inhibition a lower-affinity uptake displaceable by excess unlabelled bumetanide was evident in MDCK-N cells comprising 8 pmol/10(6) cells measured at 10 microM-[3H]bumetanide. This lower-affinity uptake was present in both co-transport-deficient mutant cell lines confirming its lack of association with inhibition of co-transport flux. In MDCK cells possessing the co-transporter, an estimate of the turnover number was made when co-transport flux and specific bumetanide uptake at 0.5 microM-[3H]bumetanide were measured in the same cell batch. At 37 degrees C this was 113 K+ ions site-1 s-1.
    [Abstract] [Full Text] [Related] [New Search]