METHYLMERCURY-INDUCED ALTERATIONS IN LUNG AND PULMONARY SURFACTANT PROPERTIES OF ADULT MICE

Exposure to methylmercuric chloride (MMC) has been shown to significan tly affect development of the lung and pulmonary surfactant system of the fetus. Preliminary results suggest it may also affect adult lung a nd associated bronchoalveolar lavage (BAL), which represents the extra cellular surfactant pool, To determine if mercury exposure has the pot ential to alter surfactant function, adult mice were treated with MMC, 15 mg/kg by intragastric intubation on 4 successive days, BAL was col lected by repeated intratracheal lavage 24 h after the last treatment. Nucleated eel numbers in lavage were determined. Tissue was prepared for scanning electron microscopy (SEM). Lavage fluid was extracted int o chloroform:methanol and phospholipid concentration determined. A sam ple of the extract was used at a constant phospholipid concentration t o measure surface activity on a bubble surfactometer. Lung weight to b ody weight ratio increased whereas total numbers of nucleated cells in BAL were not altered by MMC. SEM of samples from lungs of animals exp osed to MMC showed normal architecture. Surface tension measurements s uggest that the mean time to minimum surface tension and the minimum s urface tension were greater in BAL from mice exposed to MMC for 4 days . In addition samples of BAL were prepared for Fourier-transform infra red spectrophotometry (FT-IR). Spectra showed changes in both lipid an d protein components of BAL. Morphometric analyses of micrographs show ed that mean alveolar diameter was reduced and wall thickness increase d after mercury exposure. These results suggest that methylmercury exp osure may significantly affect surface tension characteristics and com position of BAL, possibly through leakage of edematous interstitial ti ssue. (C) 1997 Elsevier Science Ireland Ltd.