Laminin inhibits Cl- -secretion across canine tracheal epithelium

We examined the effect of laminin (a major component of the basement membrane) on potential difference (PD) and short circuit current (SCC) in both posterior epithelial membranes (native tissue) and cultured epithelial cell layers from canine trachea using an Ussing chamber. Although laminin itself did not alter the baseline values of SCC or PD, it significantly inhibited in a dose-dependent manner the isoproterenol induced SCC and PD rises of the epithelial membrane. In the cultured epithelial layer treated with amiloride, laminin did not alter the baseline values of SCC, PD or resistance (R) but it significantly inhibited the isoproterenol induced SCC rises. However, laminin did not significantly inhibit the bradykinin induced SCC rise in the cultured epithelial layer treated with amiloride. These findings indicate that laminin is a determinant in ion transport (mainly Cl- secretion) across canine tracheal epithelium, inhibiting the beta-agonist induced Cl- transport.