Laminin inhibits Cl--secretion across canine tracheal epithelium

We examined the effect of laminin (a major component of the basement membra ne) on potential difference (PD) and short circuit current (SCC) in both po sterior epithelial membranes (native tissue) and cultured epithelial cell l ayers 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 th e epithelial membrane. In the cultured epithelial layer treated with amilor ide, laminin did not alter the baseline values of SCC, PD or resistance (R) but it significantly inhibited the isoproterenol induced SCC rises. Howeve r, laminin did not significantly inhibit the bradykinin induced SCC rise in the cultured epithelial layer treated with amiloride. These findings indic ate that laminin is a determinant in ion transport (mainly Cl- secretion) a cross canine tracheal epithelium, inhibiting the beta-agonist induced Cl- t ransport. (C) 1998 Elsevier Science B.V. All rights reserved.