79 Prolonged Infusion of the Small Intestine of the Rat with Dilute Solutions of Lactic Acid

Abstract

Using a new technique for the continual infusion of solutions into the jejunum of small animals, dilute solutions of lactic acid (2.0g %–3.5 g %) were infused into the rat for 10 days and their effect on fat absorption and mucosal structure assessed. Thirty-five rats were studied in 5 groups. Control rats (water infused) ate well, gained weight, excreted normal amounts of fat (2.9 ± 1.9 %) and showed no abnormality of mucosal structure (villous length 465 ± 35 μ,). Although dilute acid (2.0 g %) produced no abnormality, groups infused with more concentrated acid did show significant increases in fat excretion (Lactic acid 2.5 %–6.5±2.1 %; 3.0g%–7.2±2.1 %). Lesions of the mucosa were found localized to the site of infusion in both of these groups, characterized by shortened villi (2.5 g%–276±95 μ, 3.0 g%–266±56 μ,) and some epithelial cell derangement at the villous tips. In some rats, fusiform extrusions of epithelial cells were seen at villous tips indicating abnormal turnover of these cells. Rats infused with 3.5 % lactic acid died within 72 hours from intestinal perforation at the infusion site. The findings suggest that the effects observed were due directly to the acid infusions and not secondary to factors such as under - nutrition or altered intestinal microflora. The observations made may not be specific for lactic acid, but they do demonstrate that intraluminal factors may impair fat absorption and mucosal structure. In this experiment, the particular factor used is an organic acid that is present in the human intestinal lumen. The infusion technique may be a valuable experimental model for future studies of the malabsorptive state. (SPR)