The function of the lung is in many aspects regulated by mechanical stimuli. To investigate the effect of mechanical forces on a native lung epithelium we used excised lungs of Xenopus laevis and recorded the transepithelial short circuit current (I_sc) in Ussing-chamber meassurements. Mechanical stress was induced by applying hydrostatic pressure from the apical side of the tissue. This decreased I_sc during several minutes by approximately 20% (n=78). The pressure-induced inhibition (I_p) was reduced under apical application of Ba²⁺ and Gd³⁺ as well as under Cl^--free conditions. If the Cl^--channel blocker niflumic acid was applied from the apical side I_p was more pronounced than under control conditions. Besides its sensitivity to various channel blockers the pressure-effect was dependent on solution osmolarity. In hyperosmotic solutions I_p was increased whereas under hyposmotic solution I_pwas diminished. The results suggest, that hydrostatic pressure influences transepithelial ion currents over a native lung epithelium through an impact on volume-regulated ion channels. Supported by DFG