PERMEABLE JUNCTIONAL COMPLEXES: The Movement of Lanthanum across Rabbit Gallbladder and Intestine

摘要: Ionic lanthanum has been used to study transepithelial ion permeation in vitro rabbit gallbladder and intestine (ileum) by adding 1 mM La3+ only the mucosal bathing solution. Transepithelial fluid transport electrical potential differences (p.d.), resistances were measured. During treatment gallbladder's rate of active solute-coupled remained constant, resistance increased, 2:1 NaCl diffusion p.d. decreased. Mucosa-to-serosa fluxes 140La3+ measured indicate a finite permeability La3+. also increased p d. ileum. Electron microscopic examination La3+-treated showed: (a) good preservation fine structure, (b) electron-opaque precipitates almost every lateral intercellular space, most frequently near apical end spaces close or within junctional complex, (c) among subjacent muscle connective tissue layers, (d) filling entire length so-called "tight" junctions. No observations made which unequivocally showed penetration into cells. micrographs similar ilea deposits penetrating complexes. These results coupled with other physiological studies that low pathway for ileum is through tight junctions A division salt-transporting epithelia two main groups, those "leaky" complexes complexes, proposed.