title: The effects of bupivacaine injection and oral nitric oxide on extraocular muscle in the rabbit.
abstract: OBJECTIVE
  Nitric oxide (NO) plays a key role in muscle regeneration, which is the primary response, observed during bupivacaine-induced extraocular muscle (EOM) hypertrophy. Our aims were to investigate the effects of bupivacaine injection into the rabbit EOM and the interaction with NO.
  
  
  METHODS
  Superior rectus (SR) muscles of 24 New Zealand albino rabbits were studied. Single muscle twitch tension (SMTT) and tetanic muscle tensions at 50, 75, and 100 Hz were recorded using a 15 V stimuli. The rabbits were equally allocated into three groups. Measurements were performed without any drug treatments in group 1. In groups 2 and 3, bupivacaine, 0.5 ml of a 0.50 % solution, was injected into the EOM, and after 21 days, measurements were performed. Oral isosorbide dinitrate (NO donor) at 20 mg/day was given each day prior to measurements in group 3.
  
  
  RESULTS
  SMTTs were 69.9 (66.7-77.6), 187.7 (114.9-252.1) and 204.2 (135.3-311.6) mg in groups 1, 2, and 3 respectively. SMTTs for both groups 2 and 3 were significantly higher than that for group 1 (p < 0.05). Compared with group 1, group 2 exhibited a 3.8-11.7 % increase in the tetanic tensions at 50, 75, and 100 Hz, but none of these differences were statistically significant. The increase was 47.5-137.5 % in group 3 relative to group 2, and the differences were statistically significant except at 100 Hz. The enlargement of the muscle fibers after bupivacaine injection was shown histopathologically.
  
  
  CONCLUSIONS
  Bupivacaine injection increased the EOM tension in rabbits to some extent. NO augmented the effect of bupivacaine.
authors.affiliation: Department of Ophthalmology, Eskisehir Osmangazi University Medical Faculty, Eskişehir, Turkey.
authors.forename: Burak
authors.initials: B
authors.lastname: Bilgin
authors.forename: Huseyin
authors.initials: H
authors.lastname: Gursoy
authors.forename: Hikmet
authors.initials: H
authors.lastname: Basmak
authors.forename: Mete
authors.initials: M
authors.lastname: Ozkurt
authors.forename: Nese
authors.initials: N
authors.lastname: Tuncel
authors.forename: Funda
authors.initials: F
authors.lastname: Canaz
authors.forename: Serap
authors.initials: S
authors.lastname: Isiksoy
authors.forename: Ertugrul
authors.initials: E
authors.lastname: Colak
mesh_terms: D000284:Administration, Oral; D000779:Anesthetics, Local / Q000494:pharmacology*; D000818:Animals; D002045:Bupivacaine / Q000494:pharmacology*; D006984:Hypertrophy; D007273:Injections, Intramuscular; D007548:Isosorbide Dinitrate / Q000008:administration & dosage*; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D018485:Muscle Fibers, Skeletal / Q000473:pathology; D020030:Nitric Oxide Donors / Q000008:administration & dosage*; D009801:Oculomotor Muscles / Q000187:drug effects*; D011817:Rabbits
chemical_list: D000779:Anesthetics, Local; D020030:Nitric Oxide Donors; D007548:Isosorbide Dinitrate; D002045:Bupivacaine