title: Anisotropic diffusion in mitral cell dendrites revealed by fluorescence correlation spectroscopy.
abstract: Fluorescence correlation spectroscopy (FCS) can be used to measure kinetic properties of single molecules in drops of solution or in cells. Here we report on FCS measurements of tetramethylrhodamine (TMR)-dextran (10 kDa) in dendrites of cultured mitral cells of Xenopus laevis tadpoles. To interpret such measurements correctly, the plasma membrane as a boundary of diffusion has to be taken into account. We show that the fluorescence data recorded from dendrites are best described by a model of anisotropic diffusion. As compared to diffusion in water, diffusion of the 10-kDa TMR-dextran along the dendrite is slowed down by a factor 1.1-2.1, whereas diffusion in lateral direction is 10-100 times slower. The dense intradendritic network of microtubules oriented parallel to the dendrite is discussed as a possible basis for the observed anisotropy. In somata, diffusion was found to be isotropic in three dimensions and 1.2-2.6 times slower than in water.
authors.affiliation: Physiologisches Institut, Universität Göttingen, D 37073 Göttingen, Germany.
authors.forename: Arne
authors.initials: A
authors.lastname: Gennerich
authors.forename: Detlev
authors.initials: D
authors.lastname: Schild
mesh_terms: D000818:Animals; D016880:Anisotropy; D055592:Biophysical Phenomena; D001703:Biophysics; D003712:Dendrites / Q000473:pathology; D004058:Diffusion; D004594:Electrophysiology; D008854:Microscopy, Electron; D009474:Neurons / Q000166:cytology; D009830:Olfactory Bulb / Q000166:cytology; D013050:Spectrometry, Fluorescence / Q000379:methods*; D013997:Time Factors; D014981:Xenopus