Abstract
Transepithelial ion transport plays an important role in the regulation of the amount and the rheological properties of bronchial secretion. The effect of grepafloxacin (GPFX), a new quinolone agent, on bioelectrical properties of airway epithelium was determined. Electrical properties of bovine tracheal epithelium cultured under an air-liquid interface condition were measured by the short-circuit technique. Addition of GPFX (100 microg/mL) to the mucosal side decreased short-circuit current (Isc) from 14.4 +/- 1.3 to 5.6 +/- 0.6 microA/cm2 (P < 0.001), and the response was accompanied by corresponding decreases in transepithelial potential difference and cell conductance. This effect was concentration dependent, and a similar response was also noted when GPFX was added to the submucosal side. The GPFX-induced decrease in Isc was not altered by the Na+ channel blocker amiloride, but was inhibited by the Cl- channel blocker diphenylamine-2-carboxylate or Cl(-)-free medium (P < 0.001, in each case). Furthermore, GPFX reduced Cl- conductance (P < 0.01) without affecting Na+ conductance of the epithelium. Grepafloxacin selectively inhibits Cl- secretion across tracheal epithelial cells, which may result in the inhibition of water secretion and, hence, the reduction of airway secretion.
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