Effects of atrazine on the gill cells and ionic balance in a neotropical fish, Prochilodus lineatus

Abstract

The effects of the herbicide atrazine on the gill of the freshwater fish Prochilodus lineatus were evaluated after exposure of fish to 2, 10 and 25μgL−1 atrazine during 48h (acute exposure) and 14d (subchronic exposure). Ions and osmolality were measured in plasma and gill samples were taken to determine the Na+/K+-ATPase (NKA) and carbonic anhydrase (CA) activities and for morphological analysis. Plasma osmolality and Na+ and Cl− ions changed depending on atrazine concentration, but atrazine exposure had no effect on the Na+/Cl− ratio. NKA activity did not change after atrazine exposure, but CA activity decreased in fish exposed to 25μgL−1 for 14d. Gill MRC density decreased after acute exposure but did not change in fish exposed to the subchronic treatment. The MRC density at the epithelial surface increased in fish exposed to 25μgL−1, and the MRC fractional area (MRCFA) increased in fish exposed to 10μgL−1. The changes in MRCs provide evidence of morphological adjustments to maintain ionic homeostasis in spite of the inhibition of CA activity at the highest atrazine concentration.