The effect of toxic particles on the electrophysiology of macrophage membranes

Changes in cell membrane potential and membrane electrical activity have been investigated in tissue culture, using guinea pig alveolar macrophages and a macrophage-like tumour cell line (P388D1), during phagocytosis of dust particles. The dusts were selected for their different abilities to haemolyse erythrocytes.

For both guinea pig and P388D1 cells, on uptake of dust, the membrane potential declined to a temporary constant value of approx 50% that of the control value. Then for the less haemolytic dusts, the membrane potential recovered to near control values, whereas for the more haemolytic dusts, the membrane potential declined further, with complete loss of mem brane potential in the case of bentonite. There was close agreement between the degree of haemolysis and the pattern of membrane potential changes, these changes being very similar for both cell systems. Hyperpolarisation activity was observed in the control cells of both series and increased markedly during the phagocytosis of dusts.

Possible reasons for the changes in the electrophysiology of cell membranes during phagocytosis are discussed.