Study on the absorption and protein binding of carbaryl, dieldrin and paraquat in rats fed on protein diet.

Carbaryl was well absorbed from the small intestine of rats. In the cytosol fraction of intestinal mucosa, it was bound to a smallmolecular component (M. W. 2,200 daltons). In serum, carbaryl was bound mainly to albumin and partly to globulins. Dieldrin was slowly absorbed from small intestine. The peak of dieldrin concentration in blood was observed 2.5 hr after the administration. Binding of dieldrin to mucosal protein in cytosol was not detectable. In serum, dieldrin was bound to lipoproteins, globulins and partly to albumin. Absorption of paraquat from the small intestine was more rapid than that of dieldrin in situ study. However, in vivo study, the absorption of paraquat was the lowest among these three chemicals. In the cytosol fraction of intestinal mucosa, paraquat was bound to a small-molecular component (M. W. 3,100 daltons). In serum, it was present in unbound fraction. In the comparative studies with protein diets, absorption of paraquat from small intestine in situ was higher in low protein diet rats than that in high protein diet rats. However, difference in absorption in vitro and in histopathological study was not noted between low protein diet rats and high protein diet rats.