title: Effect of intravenous administration of sodium-lactate on retinal blood flow in healthy subjects.
abstract: OBJECTIVE
  The present study was designed to investigate the effect of intravenously administered sodium lactate on ocular blood flow.
  
  
  METHODS
  Twelve healthy male volunteers received either sodium lactate (0.6 mol/L) or physiologic saline solution in a randomized, double-masked, two-way crossover study. Sodium lactate or placebo were administered at an infusion speed of 500 and 1000 mL/h for 30 minutes each. Blood flow measurements were performed in the last 10 minutes of the infusion periods. Retinal blood flow was calculated based on the measurement of maximum erythrocyte velocity, assessed with bidirectional laser Doppler velocimetry, and retinal vessel diameter obtained with a retinal vessel analyzer. Choroidal blood flow was assessed with laser Doppler flowmetry and laser interferometric measurement of fundus pulsation amplitude.
  
  
  RESULTS
  Administration of lactate increased blood lactate concentration from 1.3 +/- 0.4 to 3.9 +/- 0.7 mmol/L (P < 0.001) and to 7.1 +/- 1.4 mmol/L (P < 0.001) at infusion speeds of 500 and 1000 mL/h, respectively. At these blood lactate concentrations, retinal blood flow increased by 15% +/- 20% and by 24% +/- 37% (ANOVA, P = 0.01). Fundus pulsation amplitude increased by 3% +/- 6% and 10% +/- 5% (ANOVA, P = 0.04) at the two plasma lactate concentrations. Subfoveal choroidal blood flow measured with laser Doppler flowmetry tended to increase by 10% +/- 15% and 13% +/- 20% (ANOVA, P = 0.19), but this effect was not significant. Infusion of sodium lactate induced alkalosis in arterial blood taken from the earlobe (7.41 +/- 0.03 at baseline; 7.50 +/- 0.03 during lactate infusion; P = 0.001).
  
  
  CONCLUSIONS
  The data indicate that intravenously administered sodium lactate increases retinal blood flow. Whether this is related to a cytosolic redox impairment or to other hitherto unidentified mechanism remains to be clarified. Further studies are needed to determine whether lactate plays a role in regulation of choroidal blood flow.
authors.affiliation: Department of Clinical Pharmacology, University of Vienna, Austria.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Garhöfer
authors.forename: Claudia
authors.initials: C
authors.lastname: Zawinka
authors.forename: Hemma
authors.initials: H
authors.lastname: Resch
authors.forename: Marcel
authors.initials: M
authors.lastname: Menke
authors.forename: Leopold
authors.initials: L
authors.lastname: Schmetterer
authors.forename: Guido T
authors.initials: GT
authors.lastname: Dorner
mesh_terms: D000471:Alkalosis / Q000097:blood; D001783:Blood Flow Velocity; D001784:Blood Gas Analysis; D002829:Choroid / Q000098:blood supply; D018592:Cross-Over Studies; D004311:Double-Blind Method; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007262:Infusions, Intravenous; D019344:Lactic Acid / Q000097:blood; D017078:Laser-Doppler Flowmetry; D008297:Male; D012039:Regional Blood Flow; D012161:Retinal Artery / Q000502:physiology*; D012169:Retinal Vein / Q000502:physiology*; D019354:Sodium Lactate / Q000008:administration & dosage*
chemical_list: D019344:Lactic Acid; D019354:Sodium Lactate