Influence of digestive processes on the absorption and fate of quinoline ingested by rainbow trout (Oncorhynchus mykiss)

Abstract

AbstractRainbow trout were fed pelleted food containing [14C]‐quinoline to assess the relationship of digestive processes to xenobiotic pharmacokinetics. The pH of material in the stomach of rainbow trout ranged from 2.7 to 5.2 and was highly correlated (r = 0.89) with the size of the food bolus remaining. At 2 h after feeding, 67% of the quinoline was estimated to be un‐ionized and available for absorption across gastric epithelium. Quinoline was >99% un‐ionized in the alkaline environment of the intestine; however, relative concentrations in the intestine were about 8% of those measured in the stomach. Gastric absorption was consistent with known serum profiles and excretion patterns of dietary quinoline. Rates of gallbladder emptying appeared to exceed rates of hepatic bile secretion until about 8 h after a single feeding. Time since feeding influenced both the amount and concentration of quinoline‐derived radioactivity in the bile. Consecutive feedings enhanced the movement of the food bolus and associated radioactivity from the upper and midgut regions, but had no effect on disposition of quinoline.