Fig. 1. Effects of reduced ion concentrations [(A) chloride, (B) sodium] and reduced osmolarity on the transepithelial potential difference (V_te) across isolated posterior gills of Chasmagnathus granulatus acclimated to 2 salinity. Mean + S.E.M. of eight values are given in each column. Asterisks indicate statistical differences (P<0.05). Isosmotic: 517.5 mmol l^-1 Cl^- and 470.5 mmol l^-1 Na⁺ (1045 mosmol l^-1). Hyposmotic: 344.4 mmol l^-1 Cl^- and 314.5 mmol l^-1 Na⁺ (698.6 mosmol l^-1). Cl_red: chloride concentration of Hyposmotic saline, but osmolarity of Isosmotic saline. Na_red: sodium concentration of Hyposmotic saline, but osmolarity of Isosmotic saline.