Effect of the phosphorganic pesticide neguvon on the contractions of guinea-pig ileum induced by field stimulation.

The effect of the phosphorganic compound Neguvon on the contractile responses of guinea-pig ileum to electrical stimulation is studied. At low concentrations this pesticide does not affect significantly the contractions of the segments, while high concentrations block contractile responses. This effect of Neguvon probably has both pre- and postsynaptic character with respect to cholinergic transmission. Washing of the cholinesterase inhibitor fully restores the contractions induced by electrical stimulation, which shows that their inhibition is not directly connected with the inhibition of the cholinesterase activity.