609 COLCHICINE INHIBITION OF SUCRASE-ISOMALTASE LABELLING IN INTESTINAL BRUSH BORDERS

We have investigated the mechanism by which colchicine reduces disaccharidase activities in intestinal mucosa. Male CDF strain rats were injected with colchicine (0.5mg/kg body weight) freshly dissolved in physiological saline. Two hours after colchicine injection, each animal was injected with 200 μCi of 3H-leucine. Two hours later, animals were sacrificed, and homogenates and brush borders were prepared from mucosal scrapings. Aliquots were precipitated with TCA and counted for label incorporation into total protein. Sucrase was immunoprecipitated from solubilized brush borders at the experimentally determined equivalence point for each sample, using specific rabbit anti-sucrase antibody. Results (x±SEM) showed significant reductions of radiolabelling of brush border protein and immunoprecipitated sucrase,but not of total homogenate protein, and brush border sucrase activity was not significantly reduced: A significant increase in metaphase arrests in crypts of treated mucosa independently verified the effectiveness of the colchicine dose. CONCLUSIONS: These data suggest that at a dose of 0.5mg/kg body weight, colchicine significantly inhibits the movement of newly synthesized sucrase-isomaltase to the brush border of the intestinal epithelial cell.