The Journal of Membrane Biology

, Volume 99, Issue 2, pp 93–101

Ba2+-inhibitable86Rb+ fluxes across membranes of vesicles from toad urinary bladder

  • Haim Garty
  • Mortimer M. Civan
Articles

DOI: 10.1007/BF01871229

Cite this article as:
Garty, H. & Civan, M.M. J. Membrain Biol. (1987) 99: 93. doi:10.1007/BF01871229

Summary

86Rb+ fluxes have been measured in suspensions of vesicles prepared from the epithelium of toad urinary bladder. A readily measurable barium-sensitive, ouabain-insensitive component has been identified; the concentration of external Ba2+ required for half-maximal inhibition was 0.6mm. The effects of externally added cations on86Rb+ influx and efflux have established that this pathway is conductive, with a selectivity for K+, Rb+ and Cs+ over Na+ and Li+. the Rb+ uptake is inversely dependent on external pH, but not significantly affected by internal Ca2+ or external amiloride, quinine, quinidine or lidocaine. It is likely, albeit not yet certain, that the conductive Rb+ pathway is incorporated in basolateral vesicles oriented right-side-out. It is also not yet clear whether this pathway comprises the principle basolateral K+ channel in vivo, and that its properties have been unchanged during the preparative procedures. Subject to these caveats, the data suggest that the inhibition by quinidine of Na+ transport across toad bladder does not arise primarily from membrane depolarization produced by a direct blockage of the basolateral channels. It now seems more likely that the quinidine-induced elevation of intracellular Ca2+ activity directly blocks apical Na+ entry.

Key words

K+,Na+ transport intracellular Ca2+ pH membrane depolarization quinine quinidine lidocaine 

Copyright information

© Springer-Verlag New York Inc. 1987

Authors and Affiliations

  • Haim Garty
    • 1
  • Mortimer M. Civan
    • 1
  1. 1.Department of Membrane ResearchThe Weizmann Institute of ScienceRehovotIsrael
  2. 2.Departments of Physiology and MedicineUniversity of Pennsylvania School of MedicinePhiladelphia

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