Absorption of Fluoride by the Gastric Mucosa in the Rat

Open Access
Publisher Website
Google Scholar
Abstract
Approximately 100 male adult albino rats were used to measure in vivo absorption of trace amounts of aqueous inorganic fluoride from the stomach. Using surgical techniques the pylorus of the anesthetized animal (Na pentobarbital 25mg/kg, I.D.) was ligated and approximately 30 [mu]g F (as NaF) was injected into the stomach at zero time via hypodermic syringe. The total solution volume injected was one ml. Control animals received similar treatment and injections of isotonic saline solution. At intervals ranging from 5 minutes to 5 hours following F administration the entire stomach was excised, together with its contents. Preparation for fluoride analysis included addition of 0.3 g low-fluoride calcium oxide as fixative, drying and charring under infrared lamps, and ashing at 600[degree]C for 6 hours. The fluoride analysis method involved a Willard-Winter distillation from perchloric acid and thorium nitrate titration using alizarin red S as indicator. The results of these procedures suggest that absorption of fluoride by the gastric mucosa occurs rapidly, with about 50% being absorbed in the first hour, and about 16% remaining in the stomach at 5 hours. The rate of absorption is not constant, as indicated by the second derivative plot of the F disappearance curve. This suggests that several factors may influence absorption. The artificiality of the experimental design is discussed, but the data compare well with results of studies by others using more physiologic approaches.