Effects of diquat on the gastrointestinal tract of rats

After oral administration of 900 μmol of diquat/kg (LD50) to male rats there was a rapid accumulation of water in the lumen of the gastrointestinal tract of all animals. This reached a maximum 24 hr after dosing (excess water at 24 hr, approximately 14 ml/rat). Other tissues, especially blood, were dehydrated. Twenty-four hours after dosing the degree of hemoconcentration and the amount of excess water in the gastrointestinal tract were related to the amount of diquat administered. Subcutaneous injection of 90 μmol of diquat/kg caused a delayed increase in water content and dry weight of the gastrointestinal tract. Severe changes were limited to a group of fatally poisoned animals which died between 2 and 8 weeks following injection. These animals had significantly increased tissue water. Following oral administration of an LD50 of diquat to rats, deaths occurred over 9 days with about 50% of these occurring within the first 3 days. Rats which did not gain weight over the first 24 hr following dosing died within the first 3 days. Animals which did not gain weight 24 hr after an oral LD50 had significantly greater gastrointestinal water content and had a significantly more pronounced hemoconcentration than the animals in the remaining group which gained weight. It is concluded that diquat has an effect on water distribution within the body following oral administration and that early deaths are associated with rapid fluid loss into the gastrointestinal tract. Death following subcutaneous dosing appears to be an unrelated phenomenon.