Paraquat effect on the bioelectric parameters of the rabbit small intestine and its in vitro penetration

The effect of paraquat (in concentrations of 10(-4) and 10(-3) mol/l) was studied on the bioelectric parameters of rabbit small intestine. A short-lasting rise in the potential difference (PD) and some decrease of tissue resistance (R) were observed, particularly after the higher concentration. These changes indicate stimulation of the transport function of the rabbit small intestine as a result of administration of this herbicide. Other tested parameters included determination of the rate of paraquat penetration (at concentration gradient 10(-3) mol/l) across the intestinal wall from the serosal side to the mucosal side and conversely. In the latter case three experimental models were used: first--complete intestinal wall, second--intestinal wall with the serosa stripped off, and third--intestinal wall with the mucosa and serosa removed. Differences were found in these rates depending on the model used. The importance of epithelial cells of the mucosa and subepithelial layers, and mesothelium of the serosa in limiting the penetration of bipirydylium herbicides is stressed.