Uptake and Transport of Pesticidal Carbamates by Everted Sacs of Rat Small Intestine

Abstract

The absorption of five 14C-labeled pesticidal carbamate chemicals was studied using everted sacs of rat small intestine after verification that the technique of preparation and incubation of the sacs allowed consistent active transport of 14C-glucose. All five carbamates (4-chloro-2-butynyl N-(3-chlorophenyl)carbamate, 1; isopropoxyphenyl N-methylcarbamate, 2; 4-benzo-thienyl N-methylcarbamate, 3; 1-naphthyl N-methylcarbamate, 4; and 4-dimethylamino-3,5-xylyl N-methylcarbamate, 5) underwent some autodegradation during incubation in Krebs–Ringer bicarbonate medium. Carbamates 3 and 5 were the most unstable. When each of the 14C-carbamates was placed only in the mucosal fluid, a mixture of radiolabeled carbamate and degradation products was recovered from the serosal fluid. When the initial carbamate concentration (10−5 M) in the mucosal and serosal fluids was the same, there was a net increase in the total 14C concentration (14C-carbamate plus 14C-products) of the serosal fluids for carbamates 2 and 3 (and possibly 1) as follows: A net mucosal to serosal transport occurred in sacs derived from the caudal intestine for carbamates 1 and 3, and in sacs from the middle intestine for 2. Substantial tissue uptake of 14C occurred, particularly by those sacs which accomplished a net mucosal to serosal transport.