Pflügers Archiv

, Volume 316, Issue 1, pp 1–25

Two modes of Na extrusion in cells from guinea pig kidney cortex slices

  • G. Whittembury
  • F. Proverbio
Article

DOI: 10.1007/BF00587893

Cite this article as:
Whittembury, G. & Proverbio, F. Pflugers Arch. (1970) 316: 1. doi:10.1007/BF00587893

Summary

Cells from guinea pig kidney cortex slices, which have been loaded with Na and caused to lose K, by leaching at 0.6° C for 2.5 hours, extrude Na with Cl upon rewarming to 25° C in a medium without K. A subsequent rise in the K concentration in the bath at 25° C induces further net Na extrusion, 1 Na being extruded in exchange for 1 K that is taken up. When the leached tissue is rewarmed to 25°C in the presence of K in the bathing fluid (2 or 16 mM), some Na is extruded accompanied with Cl (by a mechanism that is inhibited by ethacrynic acid) and some Na is extruded maintanining a 1:1 ratio with the K that is taken up, (this system being inhibited by ouabain). Thus two modes of Na extrusion are observed, mode A that is accompanied by net Cl efflux, and that is inhibited by 2 mM ethacrynic acid, but not by 1 or 10 mM ouabain and mode B in which one K is taken up for each Na extruded. Mode B is inhibited by 1 mM ouabain and not by ethacrynic acid. DNP and anoxia inhibit both modes A and B. Insufficient doses of ouabain do not explain the refractoriness of mode A to ouabain. Ouabain and ethacrynic acid are known inhibitors of the Na−K-ATPase at much lower doses. It is concluded that both modes may originate in different Na pumps which may have different energy sources. Pump A should be efficient in the volume regulation of the cell. According to experimental procedure, both modes of Na extrusion appear of comparable magnitude. In the steady-state their relative role may be different.

Key-Words

KidneySodium TransportSodium PumpsEthacrynic AcidCardiac Glycosides

Schlüsselwörter

NiereNatrium-TransportNatriumpumpenEtacrynsäureHerzglykosiden

Copyright information

© Springer-Verlag 1970

Authors and Affiliations

  • G. Whittembury
    • 1
  • F. Proverbio
    • 1
  1. 1.Centro de Biofísica y BioquímicaInstituto Venezolano de Investigaciones Científicas (IVIC)CaracasVenezuela