title: Solid character of membrane ceramides: a surface rheology study of their mixtures with sphingomyelin.
abstract: The compression and shear viscoelasticities of egg-ceramide and its mixtures with sphingomyelin were investigated using oscillatory surface rheology performed on Langmuir monolayers. We found high values for the compression and shear moduli for ceramide, compatible with a solid-state membrane, and extremely high surface viscosities when compared to typical fluid lipids. A fluidlike rheological behavior was found for sphingomyelin. Lateral mobilities, measured from particle tracking experiments, were correlated with the monolayer viscosities through the usual hydrodynamic relationships. In conclusion, ceramide increases the solid character of sphingomyelin-based membranes and decreases their fluidity, thus drastically decreasing the lateral mobilities of embedded objects. This mechanical behavior may involve important physiological consequences in biological membranes containing ceramides.
authors.affiliation: Mechanics of Biological Systems, Departamento de Química Física I, Universidad Complutense, Madrid, Spain.
authors.forename: Elisa R
authors.initials: ER
authors.lastname: Catapano
authors.forename: Laura R
authors.initials: LR
authors.lastname: Arriaga
authors.forename: Gabriel
authors.initials: G
authors.lastname: Espinosa
authors.forename: Francisco
authors.initials: F
authors.lastname: Monroy
authors.forename: Dominique
authors.initials: D
authors.lastname: Langevin
authors.forename: Iván
authors.initials: I
authors.lastname: López-Montero
mesh_terms: D002462:Cell Membrane / Q000737:chemistry*; D002518:Ceramides / Q000737:chemistry*; D019245:Compressive Strength; D055119:Elastic Modulus; D021621:Imaging, Three-Dimensional; D019904:Polymethyl Methacrylate / Q000737:chemistry; D011312:Pressure; D012212:Rheology; D013109:Sphingomyelins / Q000737:chemistry*; D013314:Stress, Mechanical; D013499:Surface Properties; D014783:Viscosity
chemical_list: D002518:Ceramides; D013109:Sphingomyelins; D019904:Polymethyl Methacrylate