title: Delayed argon administration provides robust protection against cardiac arrest-induced neurological damage.
abstract: BACKGROUND
  Argon at a dosage of 70 % is neuroprotective, when given 1 h after cardiac arrest (CA) in rats. We investigated if a neuroprotective effect of argon would also be observed, when administration was delayed.
  
  
  METHODS
  Twenty-four male Sprague-Dawley rats, weighing between 400 and 500 g were subjected to 7 min of CA and 3 min of cardiopulmonary resuscitation. Animals were randomized to receive either 1 h of 70 % argon ventilation 1 h (n = 8) or 3 h (n = 8) after return of spontaneous circulation or no argon treatment (n = 8). For all animals, a neurological deficit score (NDS) was calculated daily for 7 days following the experiment. On day 8, rats were re-anesthetized and transcardially perfused before brains were harvested for histopathological analyses.
  
  
  RESULTS
  All animals survived. Control animals exhibited severe neurologic dysfunction at all time points as measured with the NDS. Argon-treated animals showed significant improvements in the NDS through all postoperative days, even when argon administration was delayed for 3 h. This was paralleled by a significant reduction in the neuronal damage index in the neocortex and the hippocampal CA 3/4 region in argon-treated animals, regardless of the timing of argon administration. However, animals of the delayed argon administration group additionally showed significant reductions in the basal ganglia in comparison with control animals.
  
  
  CONCLUSIONS
  Our study demonstrates that a 1-h application of argon provided a significant reduction in histopathological damage, associated with a marked improvement in functional neurologic recovery even when treatment was delayed for 3 h. This is highly significant with regard to clinical situations, where argon treatment cannot be provided timely.
authors: Department of Anesthesiology, University Hospital RWTH Aachen, Pauwelsstraße 30, 52074, Aachen, Germany, abruecken@ukaachen.de.
authors: Anne
authors: A
authors: Brücken
authors: Pinar
authors: P
authors: Kurnaz
authors: Christian
authors: C
authors: Bleilevens
authors: Matthias
authors: M
authors: Derwall
authors: Joachim
authors: J
authors: Weis
authors: Kay
authors: K
authors: Nolte
authors: Rolf
authors: R
authors: Rossaint
authors: Michael
authors: M
authors: Fries
mesh_terms: D000818:Animals; D001128:Argon / Q000008:administration & dosage / Q000494:pharmacology*; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology; D001930:Brain Injuries / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control*; D004195:Disease Models, Animal; D006323:Heart Arrest / Q000150:complications*; D008297:Male; D018696:Neuroprotective Agents / Q000008:administration & dosage / Q000494:pharmacology*; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D018696:Neuroprotective Agents; D001128:Argon