The effect of temperature on the transport of sodium and potassium by kidney cortex slices

Abstract

The maintenance of differences in electrolyte composition between intracellular and extracellular fluids in kidney slices (predominantly tubular cells) is a process which requires the expenditure of metabolic energy (see review by Davies, 1954). Whittam & Davies (1954) have shown that the rates of uptake of 24Na and 42K were very much greater at 37 than at 0°C, as would be expected if the transport process was associated with a biochemical reaction rather than a physical process such as simple diffusion through a permeable membrane, on which the effect of temperature would be smaller.It has been previously suggested (Cort & Kleinzeller, 1956 Kleinzeller & Cort, 1957 a, b) that only Na is actively transported out of renal tubular cells (at the basal membrane), while K appears to behave more passively according to gradients of concentration and electrical potential across the cell membrane. An attempt has been made to examine this question further by observation of the effect of three different temperatures (15, 25 and 300 C) on the two fluxes of greatest physiological interest, the efflux of Na (Mo, Na) and the accumulation of K (Mi, K) during incubation of kidney cortex slices. (In this paper the symbol M represents amount transported, whereas M' represents the amount transported in unit time.) Change of temperature may be expected to influence the rate of transport at the cell membrane in a complex manner since permeability, active transport and potential gradient (Q) will probably all be affected. 'D cannot be independently varied in tissue slices, and has not been measured here. In order to minimize the effect of T on D a kinetic, rather than a steadystate, approach has been adopted, the rate of transport being extrapolated to zero time by means of tangents to the curves of quantity transported versus time at the three temperatures involved. Since all the slices at the start of incubation are in approximately the same metabolic state and the same ionic environment, variation of 1D with A1T should be at a minimum with a zero time approximation.

The effect of lowering the ambient temperature on the metabolism of the new‐born pig

“…It has now been shown by a study of several muscular and glandular organs that on chilling water enters the cells and with it sodium and chloride. Some potassium is extruded (Hercus, McDowall & Mendel, 1955;Rixon & Stevenson, 1956;Leaf, 1956;Whittam, 1956;Whittam & Davies, 1956;Cort & Kleinzeller, 1958). The findings in the present investigations are in keeping with the early stages of such a process and, if so, they are the effects of a fall in the temperature of the body, not part of the metabolic response to a low ambient temperature.…”

Measurements of Electrical Potential Differences on Single Nephrons of the Perfused Necturus Kidney

“…and necessitates an active extrusion mechanism at this site. Such a localization of the sodium pump is also an integral part of cell schemes presented by Pitts (46), Whittembury et al (3,22), and others (47,48). At present it cannot be stated whether this sodium extrusion mechanism is linked with potassium uptake into the tubule cell.…”

Sodium Extrusion and Potassium Uptake in Guinea Pig Kidney Cortex Slices

“…By assuming that the passive movements change (as a function of time or of the ion concentration), the existence of a unique coupled pump, not necessarily of the 1 to 1 type, can still be maintained because changes in the passive movements would influence the net fluxes which would appear as variable. Na outflux to K influx ratios greater than 1 have been reported (44,45). A coupled pump which transfers Na ion faster than K ion would also be electrogenic and explain some of the observations that are discussed below.…”