EFFECTS OF ANESTHETICS ON MEMBRANE MOBILITY AND LOCOMOTOR RESPONSES OF HUMAN NEUTROPHILS

The morphological response of neutrophils to chemotactic factors is characterized by an immediate change (in seconds) from a spherical to an irregular shape. Within two or three minutes, the cells assume the head-tail polarity typical of locomotor cells. In this study the effects of the anaesthetic drugs, propofol and thiopentone, on the time-sequence of the morphological response of human neutrophils to the chemotactic peptide fMet-Leu-Phe were examined. At concentrations seen in the plasma during anaesthesia, both drugs inhibited both the rate and degree of the neutrophil chemotactic response. The effect of propofol was not attributable to its lipid vehicle, as 10% intralipid alone had no effect on neutrophil polarization. Plasma membrane reorganization occurs during polarization of neutrophils, resulting in morphological and functional changes which prepare the cells for chemotaxis and phagocytosis. Fluorescence recovery after photobleaching (FRAP) was used to investigate effects of the anaesthetics on membrane lipid behaviour. With a lipid probe, the proportion of mobile lipid in neutrophils exposed to propofol or thiopentone was reduced. There was a less significant reduction with intralipid which also caused reduction in velocity of lateral diffusion of the probe. These findings suggest that the inhibitory effects of anaesthetics on neutrophil locomotion are related to reductions in fluid mobility of the plasma membranes of anaesthetic-treated cells.