Pulmonary surfactant activity after severe steam inhalation injury in rabbits

Lung water content, Pao2, surface tension (in terms of hysteresis) and lecithin content of both bronchial irrigation fluid and lung homogenates were determined after severe steam inhalation injury in rabbits. At the time of a decrease in Pao2 and an increase in lung water content there was a moderate fall in pulmonary surfactant activity; as shown by a progressive decrease in the area of the hysteresis loop and a decrease of the lecithin content in both bronchial irrigation fluid and lung homogenate. It is proposed that a fall in pulmonary surfactant activity plays an important role in the pathogenesis of pulmonary oedema after inhalation injury. Successive determinations of lecithin content and/or surface tension of bronchial irrigation fluid are recommended as early diagnostic and prognostic aids in severe inhalation injury.

Lateral electromigration and diffusion of Fc epsilon receptors on rat basophilic leukemia cells: effects of IgE binding

We have used in situ electromigration and post-field relaxation (Poo, M.-m., 1981, Annu. Rev. Biophys. Bioeng., 10:245-276) to assess the effect of immunoglobulin E (IgE) binding on the lateral mobility of IgE-Fc receptors in the plasmalemma of rat basophilic leukemia (RBL) cells. Bound IgE sharply increased the receptor's electrokinetic mobility, whereas removal of cell surface neuraminic acids cut it to near zero. In contrast, we found only a small difference between the lateral diffusion coefficients (D) of vacant and IgE-occupied Fc receptors (D: 4 vs. 3 X 10(-10) cm2/s at 24 degrees C). This is true for monomeric rat IgE; with mouse IgE, the difference in apparent diffusion rates was slightly greater (D: 4.5 vs. 2.3 X 10(-10) cm2/s at 24 degrees C). This range of D values is close to that found in previous photobleaching studies of the IgE-Fc epsilon receptor complex in RBL cells and rat mast cells. Moreover, enzymatic depletion of cell coat components did not measurably alter the diffusion rate of IgE-occupied receptors. Thus, binding of fluorescent macromolecular probes to cell surface proteins need not severely impede lateral diffusion of the probed species. If the glycocalyx of RBL cells does limit lateral diffusion of the Fc epsilon receptor, it must act primarily on the receptor itself, rather than on receptor-bound IgE.