title: A method to measure permeability of red blood cell membrane to water and solutes using intrinsic fluorescence.
abstract: BACKGROUND
  Designing effective cryopreservation procedures for cells requires knowledge of permeability of cell membrane to water and solutes. To determine cell membrane permeability, one needs to measure the rate of cell volume changes in anisotonic environment. Red blood cells (RBCs) respond very quickly to changes in extracellular solutes concentration, which complicates the use of traditional methods. Preservation of RBCs from umbilical cord blood for neonatal transfusions is currently broadly discussed in the literature, but data on osmotic permeability of cord RBCs is controversial. Therefore, alternative methods to determine osmotic membrane permeability of these cells are warranted. We describe a technique to measure rapid changes in RBC volume through changes in the intensity of RBC autofluorescence.
  
  
  METHODS
  To induce osmotically-driven changes in RBC volume, we rapidly mixed human RBCs with anisotonic solutions in a stopped-flow spectroscopy system and the intensity of intrinsic RBC fluorescence was measured.
  
  
  RESULTS
  We found that change in RBC volume cause a proportional change in the intensity of RBC autofluorescence. This phenomenon occurs due to the self-quenching of RBC hemoglobin autofluorescence at high intracellular concentrations.
  
  
  CONCLUSIONS
  This novel method to determine osmotic permeability of RBCs overcomes the limitations of traditional techniques and has numerous clinical applications.
authors: Department of Laboratory Medicine and Pathology, 8249-114 Street, Edmonton, AB T6G 2R8, Canada; Centre for Innovation, Canadian Blood Services, 8249-114 Street, Edmonton, AB T6G 2R8, Canada.
authors: Mariia
authors: M
authors: Zhurova
authors: Department of Pharmacology, 970 Medical Sciences Building, University of Alberta, Edmonton, AB T6G 2H7, Canada.
authors: Aldo
authors: A
authors: Olivieri
authors: Department of Pharmacology, 970 Medical Sciences Building, University of Alberta, Edmonton, AB T6G 2H7, Canada.
authors: Andrew
authors: A
authors: Holt
authors: Department of Laboratory Medicine and Pathology, 8249-114 Street, Edmonton, AB T6G 2R8, Canada; Centre for Innovation, Canadian Blood Services, 8249-114 Street, Edmonton, AB T6G 2R8, Canada. Electronic address: jacker@ualberta.ca.
authors: Jason P
authors: JP
authors: Acker
mesh_terms: D000328:Adult; D002463:Cell Membrane Permeability / Q000502:physiology*; D004910:Erythrocyte Membrane / Q000737:chemistry* / Q000378:metabolism; D005312:Fetal Blood / Q000737:chemistry / Q000166:cytology; D005453:Fluorescence; D005990:Glycerol / Q000097:blood; D006454:Hemoglobins / Q000032:analysis; D006461:Hemolysis; D006801:Humans; D066298:In Vitro Techniques; D007231:Infant, Newborn; D012965:Sodium Chloride / Q000097:blood; D014867:Water / Q000378:metabolism*
chemical_list: D006454:Hemoglobins; D014867:Water; D012965:Sodium Chloride; D005990:Glycerol
keywords: Hemoglobin; Intrinsic fluorescence; Osmotic permeability; Red blood cell; Self-quenching; Stopped-flow system