Cytoplasmic Ca2+ determines the rate of Ca2+ entry into Mardin-Darby canine kidney-focus (MDCK-F) cells - PubMed (original) (raw)

. 1994 Jan;426(1-2):95-100.

doi: 10.1007/BF00374676.

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Cytoplasmic Ca2+ determines the rate of Ca2+ entry into Mardin-Darby canine kidney-focus (MDCK-F) cells

L Wojnowski et al. Pflugers Arch. 1994 Jan.

Abstract

Transformed Mardin-Darby canine kidney-focus (MDCK-F) cells exhibit spontaneous Ca2+ oscillations from an inositol 1,4,5-triphosphate-sensitive cytoplasmic Ca2+ store. In this study, Ca2+ entry from the extracellular space and its role in generation of oscillations were investigated by means of Ca2+ video imaging and the Fura-2/Mn2+ quenching technique. Oscillations were dependent on extracellular Ca2+ concentration and were inhibited by extracellularly applied La3+, Co2+ and Ni2+. Depolarization of the cell membrane with high K+ concentrations and the L-type Ca2+ channel blocker nifedipine had no effect on oscillations, indicating the lack of involvement of voltage-gated Ca2+ channels. Mn2+ quenching experiments disclosed significant Ca2+ influx into MDCK-F cells. The rate of this influx was constant between Ca2+ spikes, but markedly increased during the spontaneous Ca2+ spikes. Similar transient increases in Ca2+ entry could be mimicked by agents triggering intracellular Ca2+ release such as bradykinin and thapsigargin. We conclude that the plasma membrane of MDCK-F cells exhibits a marked voltage-independent Ca2+ permeability permitting Ca2+ entry into the cytoplasm. The rate of Ca2+ entry which determines the frequency of oscillations is most likely to be regulated by the cytoplasmic Ca2+ concentration.

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References

    1. Biochem J. 1988 Jul 1;253(1):81-6 - PubMed
    1. Cell Calcium. 1990 Nov-Dec;11(10):611-24 - PubMed
    1. Pflugers Arch. 1994 Jan;426(1-2):89-94 - PubMed
    1. J Biol Chem. 1989 Jul 25;264(21):12266-71 - PubMed
    1. J Biol Chem. 1992 Jan 5;267(1):108-18 - PubMed

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