Thiocyanate transport across fish intestine (Pleuronectes platessa)

Abstract

When bathed on both sides with identical chloride-containing salines the in vitro preparation of the plaice intestine maintains a negative (serosa to mucosa) short-circuit current of 107 +/- 11 muA/cm2, a transepithelial potential difference of 5.5 +/- 0.6 mV (serosa negative), and a mean mucosal membrane potential of -45.4 +/- 0.6 mV. Under these conditions the intracellular chloride activity is 32 mM. If chloride in the bathing media is partially, or completely substituted by thiocyanate the measured electrical parameters do not change but transepithelial flux determinations show a reduction in chloride fluxes and the presence of a significant thiocyanate flux. The addition of piretanide (10-4M) reduced the short-circuit current and the mucosa-to-serosa fluxes of chloride and thiocyanate; this inhibition is similar to the effect of piretanide on chloride transport in this tissue. The results indicate that thiocyanate is transported in this tissue via the piretanide-sensitive "chloride" pathway and are compared with the effects of thiocyanate on other tissues reported in the literature.