Fig. 3. Effect of osmotic manipulations on the hemolymph side of isolated posterior gills on the transepithelial potential difference (V_te). (A) Response of V_te to gradually reduced osmolarities. The data are given as percentages (± S.E.M.) of the V_te increase with Hyposmotic saline (100% response). N=20. (B) Response of V_te to ion concentration change at constant or reduced osmolarity. Mean ± S.E.M. of five values are given in each column. Asterisk indicates statistical difference (P<0.05). Isosmotic: 1045 mosmol l^-1; Hyposmotic: 698.6 mosmol l^-1; Iso_sucrose: Hyposmotic saline plus 345.4 mmol l^-1 sucrose (same osmolarity as Isosmotic saline).