Inhibition of the sodium transport by pentachlorophenol (PCP) in toad skin (Pleurodema thaul).

1. The effects of pentachlorophenol (PCP) were studied in vitro on an active ionic transporting epithelium. Ussing's technique was applied on the isolated Pleurodema thaul skin. 2. Concentrations of PCP in the range 0.003-0.043 mM caused an irreversible dose-dependent inhibition in both the short-circuit current and the potential difference. 3. Parameters of an electrical equivalent circuit were calculated applying the Isaacon's amiloride test. 4. It was also shown that PCP produced a significant increase in the O2 consumption of the skin. 5. The inhibitory action of PCP on active sodium transport in terms of the equivalent electrical circuit and the increased oxygen consumption points to an uncoupling action of PCP on the oxidative phosphorylation.