Chronic Exposure to RoundUp� Ready to Use Weed and Grass Killer Increases the Resting Membrane Potential of Crayfish Lateral Extensor Muscle Cells

Abstract

Agricultural runoff is a significant source of pollution of aquatic environments. This is of substantial concern to areas dependent on commercial farming, specifically the rural area of Grinnell, Iowa. It has previously been determined that chemical toxicity results in an increase in resting membrane potential in affected mussel muscle cells. Our research investigated the possibility that chemical toxicity can be measured in this manner in the lateral extensor muscles of crayfish, an animal native to the Grinnell area. We hypothesized that increasing concentrations of RoundUp Ready to Use Weed and Grass Killer, an herbicide commonly used in farming, would result in an increase in resting membrane potential. We exposed crayfish to environments containing various concentrations of RoundUp (0.1%, 0.5%, and 1.0%) for 70h and recorded the resting membrane potential of the right lateral extensor muscle. For each concentration we compared results against resting membrane potentials collected from control subjects raised in Grinnell tapwater. Our results showed that environmental concentrations of 1.0% of RoundUp caused significant increases in resting membrane potential compared to control subjects raised in Grinnell tap water.