title: Effects of extracellular lactate on production of reactive oxygen species by equine polymorphonuclear leukocytes in vitro.
abstract: OBJECTIVE
  To evaluate effects of extracellular lactate on viability, shape change, lactate metabolism, and reactive oxygen species (ROS) production in equine polymorphonuclear leukocytes (PMNs).
  
  
  METHODS
  PMNs isolated from equine venous blood samples.
  
  
  METHODS
  PMNs were incubated with 0 to 300mM lactate for 30 minutes before each experiment. Viability was assessed via trypan blue exclusion. Shape change was assessed via flow cytometry and light microscopy. Relative quantification of monocarboxylic acid transporter and lactate dehydrogenase lactate dehydrogenase (LDH) isotype mRNAs was performed with a real-time PCR assay. Effects of lactate at a pH of 7.4 to 6.0 on ROS production in response to phorbol 12-myristate 13-acetate, opsonized zymosan, or N-formyl-methionyl-leucyl-phenylalanine was assessed by luminol-dependent chemiluminescence.
  
  
  RESULTS
  Lactate had no effect on viability of PMNs but did alter their size and density. Monocarboxylic acid transporter 1 and lactate dehydrogenase B mRNA values were not altered. Monocarboxylic acid transporter 4 and lactate dehydrogenase A mRNA values were significantly decreased. Lactate incubation of cells significantly decreased PMN-derived luminol-dependent chemiluminescence and induced different sensitivities to stimulants (phorbol 12-myristate 13-acetate, opsonized zymosan, and N-formyl-methionyl-leucyl-phenylalanine). The response ratio to N-formyl-methionyl-leucyl-phenylalanine revealed that PMNs were primed by incubation with up to 50mM lactate, significantly increasing the production of ROS. Incubation with lactate and acidic pH caused a synergistic effect on ROS production.
  
  
  CONCLUSIONS
  Extracellular lactate potentially has a direct effect on the capacity to produce ROS by equine PMNs, which may be associated with alterations in innate immune functions within a short period after high-intensity exercise.
authors: Nihon University Veterinary Research Center, 1866 Kameino, Fujisawa, Kanagawa, Japan.
authors: Yusuke
authors: Y
authors: Echigoya
authors: Shohei
authors: S
authors: Morita
authors: Takuya
authors: T
authors: Itou
authors: Takeo
authors: T
authors: Sakai
mesh_terms: D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D005260:Female; D006736:Horses / Q000276:immunology* / Q000502:physiology; D006863:Hydrogen-Ion Concentration; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D019344:Lactic Acid / Q000378:metabolism*; D049449:Luminescence; D008297:Male; D027501:Monocarboxylic Acid Transporters / Q000378:metabolism; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D010805:Physical Conditioning, Animal; D012333:RNA, Messenger / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction / Q000662:veterinary; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D015054:Zymosan / Q000494:pharmacology
chemical_list: D027501:Monocarboxylic Acid Transporters; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D019344:Lactic Acid; D009240:N-Formylmethionine Leucyl-Phenylalanine; D015054:Zymosan; D007770:L-Lactate Dehydrogenase; D013755:Tetradecanoylphorbol Acetate