Levels of disaccharidases in the brush border membrane of equine small intestine

The disaccharides, consisting of sucrose, lactose and maltose, are hydrolysed into monosaccharides (D-glucose, D-galactose and D-fructose) by intestinal brush border enzymes: sucrase, lactase and maltase. The aim of this study to investigate changes in the brush-border membrane carbohydrate digestive enzymes. From intestinal mucosal scrapings of equine, brush border membrane vesicles were isolated. The results showed that sucrase, maltase and lactase are present in the equine small intestine. The activity of all three enzymes is highest proximally (in the duodenum and jejunum) and lower in the ileum. There was considerable variation between individual horses, however the majority showed highest disaccharidase activity in the jejunum, with some showing highest activity in the duodenum. Sucrase activity is highest in the jejunum and duodenum and lower in the ileum. Maltase activity is similar in all three regions, but slightly higher in the jejunum. Lactase activity is low in all three regions of the small intestine, slightly higher in the equine jejunum and duodenum than ileum. From this study, we can conclude that the equine small intestine digests disaccharides by the brush-border associated disaccharidases sucrase, maltase and lactase. Levels of sucrase and lactase are comparable to other species, but maltase is much higher.