title: Vasomotor effect of intravitreal juxta-arteriolar injection of L-lactate on the retinal arterioles after acute branch retinal vein occlusion in minipigs.
abstract: OBJECTIVE
  To investigate the effect of L-lactate on retinal arteriolar diameter after acute branch retinal vein occlusion (BRVO) in minipigs.
  
  
  METHODS
  Thirteen eyes of 13 minipigs were evaluated, with the animals under general anesthesia. BRVO was induced by a standard method of argon laser endophotocoagulation. Two hours after BRVO, an intravitreal, juxta-arteriolar microinjection of 50 μL L-lactate 0.5 M (pH 7.4) was performed in nine eyes. Four eyes received a microinjection of 50 μL of the solvent (pH 7.4) that was used to prepare the solution of L-lactate and served as controls. Retinal arteriolar diameter changes were measured using a retinal vessel analyzer.
  
  
  RESULTS
  Overall (n = 13), 2 hours after BRVO, there was a 9.0% ± 1.4% decrease in the retinal arteriolar diameter in the affected ares compared to baseline (P < 0.001). An increase of 26.2% ± 8.2% (P = 0.004) of the arteriolar diameter was evidenced 5 minutes after L-lactate juxta-arteriolar microinjection (n = 9) compared with the diameter before L-lactate microinjection. Thereafter, the vasodilatory effect of L-lactate persisted and remained significant until the end of the study period (27.7% ± 7.8% at 30 minutes) compared with the diameter before L-lactate microinjection (P = 0.002). Microinjection of the solvent alone (n = 4) did not produce any significant effect on the retinal arterioles, which remained constricted at all time-points (P > 0.1).
  
  
  CONCLUSIONS
  These findings demonstrate a significant arteriolar vasodilation after intravitreal juxta-arteriolar L-lactate microinjection in eyes with experimental BRVO in the affected areas. L-lactate microinjection can reverse the arteriolar vasoconstriction that occurs in acute experimental BRVO.
authors.affiliation: Laboratory of Neurobiology and Physiology of Retinal Circulation, Department of Ophthalmology, Geneva University Hospitals, Geneva, Switzerland.
authors.forename: Efstratios
authors.initials: E
authors.lastname: Mendrinos
authors.forename: Ioannis K
authors.initials: IK
authors.lastname: Petropoulos
authors.forename: Georgios
authors.initials: G
authors.lastname: Mangioris
authors.forename: Miltiadis K
authors.initials: MK
authors.lastname: Tsilimbaris
authors.forename: Domniki N
authors.initials: DN
authors.lastname: Papadopoulou
authors.forename: Aliki
authors.initials: A
authors.lastname: Geka
authors.forename: Constantin J
authors.initials: CJ
authors.lastname: Pournaras
mesh_terms: D000208:Acute Disease; D000818:Animals; D001160:Arterioles / Q000502:physiology; D058449:Intravitreal Injections; D019344:Lactic Acid / Q000008:administration & dosage*; D017075:Laser Coagulation / Q000009:adverse effects; D008845:Microinjections; D023421:Models, Animal; D009131:Muscle, Smooth, Vascular / Q000502:physiology*; D012039:Regional Blood Flow; D012161:Retinal Artery / Q000502:physiology*; D012170:Retinal Vein Occlusion / Q000209:etiology / Q000503:physiopathology*; D013552:Swine; D013556:Swine, Miniature; D014664:Vasodilation / Q000502:physiology*; D014666:Vasomotor System / Q000187:drug effects*
chemical_list: D019344:Lactic Acid