Cell electrical potentials during enhanced sodium extrusion in guinea-pig kidney cortex slices.
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.
D000818:Animals; D001693:Biological Transport, Active; D002712:Chlorides / Q000378:metabolism; D003080:Cold Temperature; D004976:Ethacrynic Acid / Q000494:pharmacology; D006168:Guinea Pigs; D006358:Hot Temperature; D066298:In Vitro Techniques; D007672:Kidney Cortex / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism; D012413:Rubidium / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism / Q000502:physiology*
D002712:Chlorides; D010042:Ouabain; D012964:Sodium; D004976:Ethacrynic Acid; D012413:Rubidium; D011188:Potassium