Abstract: To evaluate the effects of polyethylene glycol (PEG) on fish intestinal epithelium, we examined the electrophysiological responses of intestinal tissue from the puffer fish (Takifugu obscurus) using Ussing chambers. We measured the open circuit voltage, short circuit current (Isc), variation of shortcircuit current (?Isc), conductance （G）, and transepithelial potential （TEP）of the intestinal epithelium. The results showed that the residual concentration of PEG-4000 in the intestine within 6 h was 1.83 g·L^-1, which was significantly higher than that in the control (P<0.05). The residual rate was 184%. The intestine epithelial Isc of puffer fish in PEG group was 69.20 μA·cm^-2, which was significantly lower than that in the control (117.23 μA cm^-2) (P<0.05). The ?Isc of the PEG group was significantly lower than that of the control, being only 68.57% of that in the control. The average conductance of the PEG group was around 24.97mS·cm^-2, which was significantly lower than that of the control (36.22 mS·cm^-2). These results indicated that PEG-4000 was not permeable and had a high residual rate in the intestinal tract of puffer fish, which hindered ion channels and reduced the active flow of ions across the epithelium. Our results provide evidence that Ussing chamber is a valuable tool inassessing the effects of pollutants such as PEG on electrophysiological changes and ion transportation in the intestinal tract of fish.

Key words: Scapharca broughtonii, juvenile, microalgal, specific growth rate, survival.