Bioelectric parameters and sodium and chloride fluxes across the intestine of Blennius parvicornis

Abstract

Simultaneous measurements of the electric potential difference and the short-circuit current intensity were taken, as well as measurements of unidirectional fluxes of sodium and chloride in the posterior intestine of Blennius parvicornis fish.On incubating the tissue in standard Ringer solution, a potential difference of–0.9 mV, a mean net flux of sodium of 2.49 mu Eq/h x cm2 were obtained.In the absence of sodium (choline as substitute), the net chloride flux and the Isc were completely blocked.In the absence of chloride (isocyanate as substitute) the net sodium flux and the Isc were equally blocked.Ouabain lessened the sodium and chloride fluxes in the mucosa-serosa direction to the point of nulling the net fluxes of both ions.The values of the bioelectric parameters were also blocked in the presence of this inhibitor.Acetazolamide did not significantly affect the values of either the unidirectional fluxes or the net fluxes of sodium and chloride.Nor did it affect the values of the bioelectric parameters.A mechanism for the absorption of sodium and chloride is proposed in which these ions enter the cell in a coupled form and in 1:1 proportion, the transport being independent of the bicarbonate ion.