PSEUDOMONAS-AERUGINOSA INDUCES CHANGES IN FLUID TRANSPORT ACROSS AIRWAY SURFACE EPITHELIA

Fluid transport across cultures of bovine tracheal epithelium was meas ured with a capacitance probe technique. Baseline fluid absorption (J( v)) across bovine cells of 3.2 mu 1.cm(-2).h(-1) was inhibited by simi lar to 78% after 1 h of exposure to suspensions of Pseudomonas aerugin osa, with a concomitant decrease in transepithelial potential (TEP) an d increase in transepithelial resistance (R-t). Effects of P. aerugino sa were blocked by amiloride, which decreased J(v) by 112% from baseli ne of 2.35 +/- 1.25 mu 1.cm(-2).h(-1), increased Rt by 101% from basel ine of 610 +/- 257 Omega.cm(2), and decreased TEP by 91% from baseline of -55 +/- 18.5 mV. Microelectrode studies suggested that effects of P. aeruginosa on amiloride-sensitive Na absorption were due in part to a block of basolateral membrane K channels. In the presence of Cl tra nsport inhibitors [5-nitro-2-(3-phenylpropylamino)-benzoic acid, H-2-D IDS, and bumetanide], P. aeruginosa induced a fluid secretion of simil ar to 2.5 +/- 0.4 mu 1.cm(-2).h(-1) and decreased R-t without changing TEP. However, these changes were abolished when the transport inhibit ors were used in a medium in which Cl was replaced by an impermeant or ganic anion. Filtrates of P. aeruginosa suspensions had no effect on J (v), TEP, or R-t. Mutants lacking exotoxin A or rhamnolipids or with d efective lipopolysaccharide still inhibited fluid absorption and alter ed bioelectrical properties. By contrast, mutations in the rpoN gene e ncoding a sigma factor of RNA polymerase abolished actions of P. aerug inosa. In vivo, changes in transepithelial salt and water transport in duced by P. aeruginosa may alter viscosity and ionic composition of ai rway secretions so as to foster further bacterial colonization.