TRAPPING OF CS-134(-SKIN EPITHELIUM AS A FUNCTION OF SHORT-CIRCUIT CURRENT() IN FROG)

In the sodium/potassium pump of the isolated frog skin epithelium, Cs- 134(+) can to a certain degree replace potassium. If Cs-134(+) in almo st a carrier-free amount is added to the solution bathing the inside o f the frog skin in an Ussing chamber, there will be an uptake of Cs-13 4(+) into the epithelium cells which is proportional to the short circ uit current. Transepithelial flux of Cs-134(+) in leaky epithelia, for instance small intestine and frog skin glands, indicates a paracellul ar pathway. The consequences of these findings for the recycling-theor y are discussed.