Procaine-Mediated Modification of Membranes and of the Response to X Irradiation and Hyperthermia in Mammalian Cells

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Abstract
Procaine, a membrane-specific agent, protected the response of oxygenated mammalian cells toward X-irradiation in vitro. The drug also potentiated hyperthermic killing of cells. To study the mechanisms underlying the action of procaine as a modifier of cell injury in X-irradiated and heated cells, the effects of procaine on cellular morphology, membrane fluidity and cellular electrokinetic properties were studied. Procaine can reversibly influence the cellular morphology. Using scanning electron microscopy, numerous smooth blebs were seen on the cell surface of normal or SV40-transformed 3T3 mouse fibroblasts treated with procaine. When 1,6-diphenyl-1,3,5-hexatriene was used as a membrane probe, the overall fluidity of cell membranes from 3T3 cells grown as monolayers or L5178Y lymphoma cells grown in suspensions was not significantly changed by procaine; when perylene was used as a probe, the overall fluidity of cell membranes of procaine-treated cells increased significantly. Procaine altered the electrophoretic mobility of cells. Procaine may exert its modification of radiation- and heat-induced effects via a still elusive membrane-mediated mechanism(s). The use of membrane-active agents with different specificities as tools to probe the role of membranes in the radiation or heat response of cells is anticipated.