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Cell electrical potentials during enhanced sodium extrusion in guinea‐pig kidney cortex slices.
Author(s) -
Proverbio F,
Whittembury G
Publication year - 1975
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1975.sp011070
Subject(s) - hyperpolarization (physics) , ouabain , biophysics , extracellular , membrane potential , chemistry , sodium , potassium , intracellular , biochemistry , stereochemistry , biology , organic chemistry , nuclear magnetic resonance spectroscopy
1. Experiments were performed on outermost slices of the guinea‐pig kidney which are mainly made up of proximal tubular cells. 2. Kidney cells loaded with Na+ by chilling at 0.6 degrees C for 2.5 hr, when subsequently rewarmed to 25 degrees C in a medium containing 16 mM‐K+ extrude Na+ at enhanced speed for about 10 min. This Na+ movement is accompanied by efflux of Cl and influx of K+. 3. Measurements of cell potential during enhanced Na+ extrusion show that cells hyperpolarize to values about 30 mV more negative than the K+ equilibrium potential. 4. This hyperpolarization is only partly inhibited by 1 mM ouabain or by 2 mM ethacrynic acid but both agents added together suppress it completely. 5. With 16 mM‐Rb instead of 16 mM‐K the hyperpolarization is smaller. 6. A diminished extracellular K+ concentration outside of the cells, within the slice, can account for only a small part of the hyperpolarization. 7. The hyperpolarization is proportional to the rate of Na+ pumping. 8. Cl‐ seems to shunt the hyperpolarization to a greater extent than K+. 9. It is concluded that Na+ extrusion is capable of transferring electric charge across the membrane.