ABSTRACT
Measurements of electrical-potential difference (TEP) and Na+ efflux, across the integument have been made for Corophtum volutator acclimated to 85 or 15%SW.
The TEP of acclimated animals in 85 or 15%SW is 1·4 mV or 11·1 mV respectively (haemolymph negative). For acclimated animals, . unidirectional Na+ efflux is 154·3 nmol mg−1 body weight h−1 in 85%SW [efflux rate constant (k) = 0·70 h−1] and approximately 35·5 nmol mg−1 h−1 in 15%SW (k = 0·50h−1 in 10%SW).
The results indicate that Na+ and Cl−are passively distributed across the ion-permeable (gill) integument of acclimated animals in 85%SW, but that active uptake of Cl−, and possibly Na+ also, occurs across the gills of acclimated animals in 15%SW. The ion transport mechanisms appear to effect electroneutral transfers across the gill integumental epithelium.
Corophium volutator gill integument has a high permeability to ions; permeability to Na+(PNa) is 7·5x 10−8ms−1, and the ratio PCL/PNa is 0·45, for animals acclimated to either salinity. The resistance of the gill thelium of acclimated animals has been calculated to be·3×10−3Ωm2 and 2·0×10−2Ωm2 in 85 and 15%SW respectively.
