title: Tracheal epithelial damage alters tracer fluxes and effects of tracheal osmolaity in sheep in vivo.
abstract: Tracheal osmolaity affects blood flow and the flux of a tracer, technetium-99m-labeled diethylenetriamine pentaacetic acid (99mTc-DTPA), from tracheal lumen to venous blood in anesthetized sheep. Hyperosmolar liquids increase blood flow and slightly decrease 99mTc-DTPA flux, whereas hyposmolar liquids have no effect on blood flow and greatly increase 99mTc-DTPA flux. We have now investigated whether epithelial damage induced by exposure of the tracheal lumen to a detergent (0.2% Triton X-100) alters these effects. A tracheal artery was perfused, and tracheal venous blood was collected. The initial tracheal volume was 12.8 +/- 0.7 ml. Triton X-100 greatly increased the permeability coefficient for 99mTc-DTPA from -2.1 x 10(-7) to -240 x 10(-7) cm/s. Hyperosmolar Krebs-Henseleit solution (KH; 739 +/- 6 mosmol/kg) increased arterial (+14.3%) and venous (+21.5%) flows and decreased 99mTc-DTPA output by 51.7%. Water flux into the lumen (+0.3 +/- 0.1 ml) was not significant, and the osmolality decreased by 99 +/- 9 mosmol/kg. Hyposmolar KH (124 +/- 2 mosmol/kg) had no effect on arterial and venous flows (-1.3% for both), and the increase in 99mTc-DTPA output (+8.3%) was small and not significant. The volume decreased by 0.4 +/- 0.1 ml, and the osmolaity increased by 36 +/- 4 mosmol/kg. Thus epithelial damage greatly increases the baseline permeability of the tracheal wall to 99mTc-DTPA. It does not alter the qualitative effects of hypersomolar KH on blood flow and 99mTc-DTPA output but does reduce the effect of hyposmolar KH on 99mTc-DTPA output. The latter effect may be a consequence of the reduced net water movement in response to non-isosmolar solutions after epithelial damage.
authors.affiliation: Department of Physiology, St. George's Hospital Medical School, London, United Kingdom.
authors.forename: U M
authors.initials: UM
authors.lastname: Wells
authors.forename: A J
authors.initials: AJ
authors.lastname: Woods
authors.forename: Z
authors.initials: Z
authors.lastname: Hanafi
authors.forename: J G
authors.initials: JG
authors.lastname: Widdicombe
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D001834:Body Water / Q000378:metabolism; D002463:Cell Membrane Permeability / Q000502:physiology; D004848:Epithelium / Q000378:metabolism / Q000473:pathology / Q000502:physiology; D005260:Female; D017830:Octoxynol / Q000494:pharmacology; D009994:Osmolar Concentration; D012039:Regional Blood Flow / Q000502:physiology; D012756:Sheep; D016284:Technetium Tc 99m Pentetate; D014132:Trachea / Q000098:blood supply / Q000473:pathology / Q000502:physiology*
chemical_list: D017830:Octoxynol; D016284:Technetium Tc 99m Pentetate