||Rat alveolar macrophage cells were removed by bronchoalveolar lavage using calcium- and magnesium-free Hank's salt solution. The identity of the harvested cells was confirmed using electronic cell sizing and transmission electron microscopy. Cell yield for each preparation was determined with a Coulter electronic cell counter (Model ZB, Coulter Instruments, Hialeah, FL). Cell size (mean cell volume) and the purity of the preparation were determined using an electronic cell sizing attachment (Lane and Mehta, 1990, primary source). Cell diameter was calculated from the cell volume data, assuming a spherical shape, as follows: V=(4/3)×pr^3, where V is the mean cell volume and r the radius. Cell water was calculated, assuming an average cell water content of 70%, as follows: cell water=(mean cell volume)/(%cell water). Calculated according to volume of 1456 µm^3 assuming spherical shape.