title: Effects of low glucose concentrations on oxygen consumption rates of intervertebral disc cells.
abstract: METHODS
  Investigation of the effects of low glucose concentrations on the oxygen consumption rates of intervertebral disc cells.
  
  
  OBJECTIVE
  To determine the oxygen consumption rate of porcine anulus fibrosus (AF) cells at different glucose concentrations and to examine the differences in the oxygen consumption rate between AF and nucleus pulposus (NP) cells at different glucose levels.
  
  
  BACKGROUND
  Poor nutrient supply has been suggested as a potential mechanism for degeneration of the intervertebral disc (IVD). Distribution of nutrients in the IVD is strongly dependent on transport properties of the tissue and cellular metabolic rates. Previous studies have shown dependence of oxygen consumption rate of IVD cells on oxygen tension, pH levels, and glucose levels outside the physiologic range. However, the oxygen consumption rate of AF cells at in vivo glucose levels has not been investigated.
  
  
  METHODS
  IVD cells were isolated from the outer AF and NP of 4- to 5-month-old porcine lumbar discs. The changes in oxygen tension were recorded when cells were cultured in sealed metabolism chamber. The oxygen consumption rate of cells was determined by theoretical curve fitting using the Michaelis-Menten equation.
  
  
  RESULTS
  The outer AF cells cultured in high glucose medium (25 mmol/L) exhibited the lowest oxygen consumption rate, whereas no significant differences in oxygen consumption rates were found among outer AF cells cultured at physiologic glucose levels (i.e., 1 mmol/L, 2.5 mmol/L, 5 mmol/L). The oxygen consumption rate of NP cells was significantly greater than that of outer AF cells.
  
  
  CONCLUSIONS
  Since the oxygen consumption rates determined in this study are comparable to the findings in the literature, this study has developed a new alternative method for determining oxygen consumption rate. The oxygen consumption rates of IVD cells reported in this study will be valuable for theoretically predicting local oxygen concentrations in IVD, which can provide a better understanding of transport of oxygen in the discs.
authors.affiliation: College of Dental Medicine, Nova Southeastern University, Fort Lauderdale, FL, USA.
authors.forename: Chun-Yuh C
authors.initials: CY
authors.lastname: Huang
authors.forename: Tai-Yi
authors.initials: TY
authors.lastname: Yuan
authors.forename: Alicia R
authors.initials: AR
authors.lastname: Jackson
authors.forename: Larry
authors.initials: L
authors.lastname: Hazbun
authors.forename: Christopher
authors.initials: C
authors.lastname: Fraker
authors.forename: Wei Yong
authors.initials: WY
authors.lastname: Gu
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005947:Glucose / Q000378:metabolism* / Q000494:pharmacology; D007403:Intervertebral Disc / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008159:Lumbar Vertebrae; D008954:Models, Biological; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption / Q000187:drug effects; D015203:Reproducibility of Results; D013552:Swine
chemical_list: D005947:Glucose; D010100:Oxygen