THE EFFECTS OF THE ORGANOPHOSPHOROUS INSECTICIDES DURSBAN(TM) AND LORSBAN(TM) ON THE CILIATED EPITHELIUM OF THE FROG PALATE IN-VITRO

The ciliotoxic potential of the organophosphorous insecticides Dursban (TM) and Lorsban(TM), their active ingredient, chlorpyrifos, and their carrier ingredients (Blanks) were assessed. Since chlorpyrifos inhibi ts acetylcholinesterase, the acetylcholine-innervated ciliated epithel ial cultures of frog palate were used as the model. All compounds caus ed a decrease in frequency of ciliary beat over time. EC(50) values fo llowed the same order as the time to inhibition. The orders were Lorsb an > Dursban > chlorpyrifos, and Lorsban > Dursban similar to Lorsban Blank > Dursban Blank. Stimulation of ciliary beating occurred immedia tely after exposure to all compounds, followed by inhibition. Dursban, Lorsban, and both Blanks elicited stimulatory effects in the presence of atropine. Atropine only blocked the initial stimulatory response w ith chlorpyrifos. In addition to chlorpyrifos, some component(s) of th e inert ingredients were initially stimulatory but ultimately inhibito ry to ciliary beating in the frog palate model. All compounds caused m itochondrial damage, including swelling, disruption of cristae, and lo ss of matrix.