title: Excess plasma membrane and effects of ionic amphipaths on mechanics of outer hair cell lateral wall.
abstract: The interaction between the outer hair cell (OHC) lateral wall plasma membrane and the underlying cortical lattice was examined by a morphometric analysis of cell images during cell deformation. Vesiculation of the plasma membrane was produced by micropipette aspiration in control cells and cells exposed to ionic amphipaths that alter membrane mechanics. An increase of total cell and vesicle surface area suggests that the plasma membrane possesses a membrane reservoir. Chlorpromazine (CPZ) decreased the pressure required for vesiculation, whereas salicylate (Sal) had no effect. The time required for vesiculation was decreased by CPZ, indicating that CPZ decreases the energy barrier required for vesiculation. An increase in total volume is observed during micropipette aspiration. A deformation-induced increase in hydraulic conductivity is also seen in response to micropipette-applied fluid jet deformation of the lateral wall. Application of CPZ and/or Sal decreased this strain-induced hydraulic conductivity. The impact of ionic amphipaths on OHC plasma membrane and lateral wall mechanics may contribute to their effects on OHC electromotility and hearing.
authors.affiliation: Department of Otorhinolaryngology and Communicative Science, Baylor College of Medicine, Houston, Texas 77030, USA. nmorimoto@nch.go.jp
authors.forename: Noriko
authors.initials: N
authors.lastname: Morimoto
authors.forename: Robert M
authors.initials: RM
authors.lastname: Raphael
authors.forename: Anders
authors.initials: A
authors.lastname: Nygren
authors.forename: William E
authors.initials: WE
authors.lastname: Brownell
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000378:metabolism*; D048429:Cell Size; D002746:Chlorpromazine / Q000737:chemistry / Q000494:pharmacology; D006168:Guinea Pigs / Q000502:physiology; D018072:Hair Cells, Auditory, Outer / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D066298:In Vitro Techniques; D008433:Mathematics; D008954:Models, Biological; D020156:Salicylic Acid / Q000737:chemistry / Q000494:pharmacology; D013314:Stress, Mechanical; D013396:Suction; D022161:Transport Vesicles / Q000378:metabolism*
chemical_list: D020156:Salicylic Acid; D002746:Chlorpromazine