摘要：Bacitracin is an antibacterial cyclic dodecapeptide produced by Bacillus licheniformin. Besides antibacterial activity, it is reported to have a protease inhibitory activity and an absorption enhancing action. Here we determined the effects of bacitracin on transport of water-soluble dye fluoresceinisothiocyanate (FITC)-dextran across the rat intestinal mucosal membrane using an electrophysiological technique. Bacitracin enhanced the intestinal mucosal-to-serosal transport of FITC-dextran in concentration-dependent and pH-dependent manners. In particular, the addition of bacitracin to the mucosal side led to a remarkable enhancement of FITC-dextran transport across the colonic membrane. Furthermore, its exhibition of transport enhancement required the existence of metal divalent cations, Ca2+ and Mg2+, in the mucosal compartment. Electrophysiological study using voltageclamp technique revealed that a relatively lower concentration of bacitracin (5 mM) enhanced the transport of 6-carboxyfluorescein via a paracellular pathway in the colonic membrane and higher concentration of bacitracin (20 mM) affects both transcellular and paracellular routes, resulting in significant enhancement of 6-carboxyfluorescein across the colonic membrane. These findings might provide the useful information for enhancing the intestinal transport of poorly a sbsorbable drugs by bacitracin which has multiple functions.
关键词：bacitracin;fluoresceinisothiocynate (FITC)-dextran;Ussing type chamber;electrophysiology;voltage clamp method;passive transport
