Inhibition of phagocytosis and plasma membrane mobility of the cultivated macrophage by cytochalasin B. Role of subplasmalemmal microfilaments.
Functional and morphologic effects of cytochalasin B on the cultivated macrophage were examined to determine the basis for plasma membrane movements of the type required for endocytosis and/or spreading on a substratum. Inhibition of phagocytosis and changes in cell shape by cytochalasin B exhibited nearly identical dose-response curves requiring 2-5 x 10(-6) M and 1-2 x 10(-5) M cytochalasin B to inhibit these functions by 50% and 100%, respectively. In contrast, hexose transport was ten times more sensitive to the drug requiring 2-3 x 10(-7) M cytochalasin B to achieve 50% inhibition of 2-deoxyglucose uptake. Inhibition of phagocytosis and changes in cell shape could not be explained solely by drug effects on hexose transport. Analysis of serial thin sections showed that cytochalasin B doses inhibitory for hexose transport had no effect on distribution or organization of either of the two subplasmalemmal microfilament types. However, cytochalasin B concentrations (2.0 x 10(-5) M) that inhibited phagocytosis and altered cell shape disorganized and/or disrupted oriented bundles of 40-50-A subplasmalemmal microfilaments, but had no effect on the microfilamentous network. Comparative dose-response studies showing positive correlations among cytochalasin B effects on phagocytosis, changes in cell shape, and alterations in oriented subplasmalemmal microfilament bundles provide additional support for the hypothesis that microfilamentous structures play a role in translocation of plasma membrane required for endocytosis and cell motility.
D000818:Animals; D002462:Cell Membrane / Q000187:drug effects*; D002465:Cell Movement / Q000187:drug effects*; D003571:Cytochalasin B / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005947:Glucose / Q000378:metabolism; D006601:Hexoses / Q000378:metabolism; D002479:Inclusion Bodies / Q000502:physiology*; D008264:Macrophages / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D051379:Mice; D008855:Microscopy, Electron, Scanning; D008858:Microscopy, Phase-Contrast; D010587:Phagocytosis / Q000187:drug effects*
D006601:Hexoses; D003571:Cytochalasin B; D005947:Glucose