DESIGN AND PERFORMANCE OF AN INTEGRATED FLUORESCENCE, POLARIZED FLUORESCENCE, AND BREWSTER-ANGLE MICROSCOPE LANGMUIR TROUGH ASSEMBLY FOR THE STUDY OF LUNG SURFACTANT MONOLAYERS

We describe an integrated fluorescence, polarized fluorescence, and Br ewster angle microscope/Langmuir trough assembly. This apparatus was s pecifically designed for the study of lung surfactant (LS) monolayers, and is well suited for the study of other lipid/protein monolayer sys tems. The apparatus can be operated simultaneously in both the fluores cence and Brewster angle modes under a wide range of conditions, inclu ding physiological subphases and temperatures. The combination of info rmation obtained from these microscopy techniques facilitates the iden tification of the composition of coexisting phases, allows us to syste matically study the effects of specific proteins on lipid monolayers, and eliminates possible artifacts inherent to fluorescence. To demonst rate this system we present images of mixed monolayers of the anionic and unsaturated lipid components of LS and show that synergistic inter actions between certain LS proteins and these lipids hold the key to t he proper functioning of LS monolayers. (C) 1997 American Institute of Physics.