TY - JOUR

T1 - Pathways for chloride and sodium transport across toad skin

AU - Bruus, K.

AU - Kristensen, P.

AU - Larsen, Erik Hviid

PY - 1976

Y1 - 1976

N2 - The voltage dependecies of Na and Cl fluxes were investigated in the isolated toad skin. With Cl-Ringer's on both sides Cl outflux varied very little with clamping voltage. The same was true for the influx of Cl at depolarizing voltages (psii -psio lessthan0 mV), wheras hyperpolarization led to a marked increase in this flux. A net chloride influx under short circuit conditions indicated active transport of chloride. The outflux of Cl was a saturable function of outside Cl concentration. The outflux of urea was hardly affected by raising outside Cl concentration, and the effect of varying outside nitrate concentration on Cl outflux was likewise small. Both influx and outflux could be inhibited partially bt acetazolamide. The outflux of Na varied with the clamping voltage as would be expected for an ion transported by electrodiffusion, and it was shown that amiloride had no effect on Na outflux, so it was concluded that the Na outflux route is particular. In the absence of Cl in the outside solution a small outflux of Cl persists. Also this flux varied with the clamping voltage according to laws for electrodiffusion. The variation of the ratio of sodium outflux to chloride outflux with clamping voltage indicated free passive diffusion of both these ions under the conditions mentioned. A comparison of the outfluxes of Na and Cl in skins bathed with gluconate Ringer's outside showed that the outflux route of these two ions was cation selective (PNa/PCl=1.88). When the paracellular leak pathway of the skins was opened by exposing the outside to hyperosmolar urea solutions, the ratio of the transport numbers was found to be TNa/TCl=1.71. The roles of the two ions in determining the steady state current-voltage relationships were compared. At hyperpolarizing voltages most or all of the clamping current was carried by an inward Cl flux. By depolarization sodium influx plays an increasing role with increasing depolarization. Under short circuit conditions active chloride transport was found to contribute to the short circuit current.

AB - The voltage dependecies of Na and Cl fluxes were investigated in the isolated toad skin. With Cl-Ringer's on both sides Cl outflux varied very little with clamping voltage. The same was true for the influx of Cl at depolarizing voltages (psii -psio lessthan0 mV), wheras hyperpolarization led to a marked increase in this flux. A net chloride influx under short circuit conditions indicated active transport of chloride. The outflux of Cl was a saturable function of outside Cl concentration. The outflux of urea was hardly affected by raising outside Cl concentration, and the effect of varying outside nitrate concentration on Cl outflux was likewise small. Both influx and outflux could be inhibited partially bt acetazolamide. The outflux of Na varied with the clamping voltage as would be expected for an ion transported by electrodiffusion, and it was shown that amiloride had no effect on Na outflux, so it was concluded that the Na outflux route is particular. In the absence of Cl in the outside solution a small outflux of Cl persists. Also this flux varied with the clamping voltage according to laws for electrodiffusion. The variation of the ratio of sodium outflux to chloride outflux with clamping voltage indicated free passive diffusion of both these ions under the conditions mentioned. A comparison of the outfluxes of Na and Cl in skins bathed with gluconate Ringer's outside showed that the outflux route of these two ions was cation selective (PNa/PCl=1.88). When the paracellular leak pathway of the skins was opened by exposing the outside to hyperosmolar urea solutions, the ratio of the transport numbers was found to be TNa/TCl=1.71. The roles of the two ions in determining the steady state current-voltage relationships were compared. At hyperpolarizing voltages most or all of the clamping current was carried by an inward Cl flux. By depolarization sodium influx plays an increasing role with increasing depolarization. Under short circuit conditions active chloride transport was found to contribute to the short circuit current.

KW - Acetazolamide

KW - Animals

KW - Anura

KW - Biological Transport

KW - Biological Transport, Active

KW - Cell Membrane Permeability

KW - Chlorides

KW - Epithelial Cells

KW - Epithelium

KW - Extracellular Space

KW - Female

KW - Ion Exchange

KW - Osmolar Concentration

KW - Skin

KW - Sodium

U2 - 10.1111/j.1748-1716.1976.tb10233.x

DO - 10.1111/j.1748-1716.1976.tb10233.x

M3 - Journal article

C2 - 1274636

VL - 97

SP - 31

EP - 47

JO - Acta Physiologica Scandinavica

JF - Acta Physiologica Scandinavica

SN - 0001-6772

IS - 1

ER -