Transcellular Ion Transport and Bioelectric Potential

Abstract

Summary

The transient effect of temperature on the electrical potential of transcellularly transporting epithelial cells of frog skin and toad bladder has been studied. The Q₁₀ of the transepithelial potential difference is 1.51. This temperature effect is much larger than what can be expected if this bioelectric potential had been strictly due to passive diffusion of ions across permselective membranes. In the study of the transient effects on ion fluxes it has been observed that the effect of temperature is more pronounced on the inward flux of Na ion than on its outward flux. Na-influx increases with temperature, as does the short-circuit current. Both of these parameters increase instantly with the elevated tissue temperature. The inward and outward fluxes of K+ are not significantly affected by temperature. Thus, it is concluded that the passively diffusing K ions are only slightly affected by temperature. On the other hand, the active transcellular transport of Na ions is very sensitive to temperature. It is proposed that a biochemical electrogenic mechanism is likely to underlie the process of transcellular transport of sodium ions and also the generation of the associated electrical potential.