title: Diffusion coefficients in the lateral intercellular spaces of Madin-Darby canine kidney cell epithelium determined with caged compounds.
abstract: The diffusion coefficients of two caged fluorescent dyes were measured in free solution and in the lateral intercellular spaces (LIS) of cultured Madin-Darby canine kidney (MDCK) cells after photoactivation by illumination with a continuous or pulsed UV laser. Both quantitative video imaging and a new photometric method were utilized to determine the rates of diffusion of the caged fluorescent dyes: 8-((4,5-dimethoxy-2-nitrobenzyl)oxy)pyrene-1,3,6-trisulfonic acid (DMNB-HPTS) and (4,5-dimethoxy-2-nitrobenzyl) fluorescein dextran (10,000 MW) (DMNB-caged fluorescein dextran). The diffusion coefficients at 37 degrees C in free solution were 3.3 x 10(-6) cm2/s (HPTS) and 0.98 x 10(-6) cm2/s (10,000 MW dextran). Diffusion of HPTS within nominally linear stretches of the LIS of MDCK cells grown on glass coverslips was indistinguishable from that in free solution, whereas dextran showed a 1.6 +/- 0.5-fold reduction in diffusivity. Measurements of HPTS diffusion within the LIS of multicellular regions also exhibited a diffusivity comparable to the free solution value. The restriction to diffusion of the dextran within the LIS may be due to molecular hindrance.
authors.affiliation: Laboratory of Kidney and Electrolyte Metabolism, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: P
authors.initials: P
authors.lastname: Xia
authors.forename: P M
authors.initials: PM
authors.lastname: Bungay
authors.forename: C C
authors.initials: CC
authors.lastname: Gibson
authors.forename: O N
authors.initials: ON
authors.lastname: Kovbasnjuk
authors.forename: K R
authors.initials: KR
authors.lastname: Spring
mesh_terms: D000818:Animals; D002460:Cell Line; D003911:Dextrans; D004058:Diffusion; D004285:Dogs; D004847:Epithelial Cells / Q000502:physiology; D005110:Extracellular Space / Q000502:physiology*; D005452:Fluoresceins; D005456:Fluorescent Dyes; D007668:Kidney; D007700:Kinetics; D007834:Lasers; D008856:Microscopy, Fluorescence / Q000295:instrumentation / Q000379:methods; D018715:Microscopy, Video / Q000379:methods; D008962:Models, Theoretical; D010477:Perfusion; D011721:Pyrenes; D013451:Sulfonic Acids; D013997:Time Factors; D014466:Ultraviolet Rays
chemical_list: C113815:(4,5-dimethoxy-2-nitrobenzyl)fluorescein dextran; C113814:8-((4,5-dimethoxy-2-nitrobenzyl)oxy)pyrene-1,3,6-trisulfonic acid; D003911:Dextrans; D005452:Fluoresceins; D005456:Fluorescent Dyes; D011721:Pyrenes; D013451:Sulfonic Acids