Fig. 4. Plasma concentrations (mmol l^-1) of Cl^-, Na⁺ and urea in Scyliorhinus canicula at 0h (black columns), 0.5h (light grey columns) and 3h (dark grey columns) following administration of 1 ml kg^-1 body mass of (A) 20% NaCl (N=9), (B) 2 mol l^-1 mannitol (N=7), (C) 75% sucrose (N=7) and (D) vehicle (N=4). Results are expressed as means + S.E.M. Plasma sodium concentration was significantly (^**P<0.01) reduced relative to the 0h value 30min after administration of 75% sucrose (Student's t-test).