Interfacial tension at plasma membranes of normal and virustransformed fibroblast cell cultures

Abstract

Interfacial tensions of the outer plasma membrane of normal and transformed in vitro cultures of mouse fibroblasts have been characterized by using the method of contact angles.

Contact angles of 3T3 cells are independent of cell density on the culture plate, whereas those of SV40-3T3 and PY-3T3 cells decrease with cell density. Treatment of 3T3 cells with calf serum as a stimulant of cell proliferation leads to a decrease of contact angle at all cell densities, whereas serum treatment of PY-3T3 cells does not lead to a decrease of contact angle at higher cell density. Treatment of 3T3 or SV40-3T3 cells with concananvalin A as an inhibitor of cell proliferation leads to an increase of the contact angles. When interfacial tensions are derived from contact angle data by using the thermodynamic theory of Neumann and coworkers, figures in the range of 0.1–3 mNm⁻¹ are obtained.

These and earlier results are consistent with the hypothesis of a lateral phase separation in the plasma membrane of the cells, triggered by serum treatment and mediated by a variation of Ca⁺⁺-binding to negatively charged ligands in the membrane.