Glutathione reductase activity.

<p>Glutathione reductase (GR) activity (nmol NADPH/min/mg protein) in liver of fed and fasted fish during acclimation to different salinities and exposure to HEA. Values are mean ± S.E. Asterisk (*) indicates a significant difference between the ammonia exposed fish and its respective control at each salinity (*<i>P</i> < 0.05; **<i>P</i> < 0.01), bullet (•) indicates a significant difference between experimental salinities (20 ppt -2.5 ppt) and the 32 ppt-acclimated fish at the same sampling period (^•<i>P</i> < 0.05), dagger (†) denotes the significant difference between fed fish and its respective fasted fish counterpart (^†<i>P</i> < 0.05).