Trapping of 134CS+ in frog skin epithelium as a function of short circuit current

In the sodium/potassium pump of the isolated frog skin epithelium, 134CS+ can to a certain degree replace potassium. If 134CS+ in almost a carrier-free amount is added to the solution bathing the inside of the frog skin in an Ussing chamber, there will be an uptake of 134 CS+ into the epithelium cells which is proportional to the short circuit current. Transepithelial flux of 134CS+ in leaky epithelia, for instance small intestine and frog skin glands, indicates a paracellular pathway. The consequences of these findings for the recycling-theory are discussed.