Postconditioning by xenon and hypothermia in the rat heart in vivo.
OBJECTIVE
Hypothermia protects against myocardial reperfusion injury. However, inducing hypothermia takes time, which makes it unsuitable as an emergency treatment. Combining mild hypothermia with low-dose xenon, applied either simultaneously or one after the other, protects the neonatal rat brain against reperfusion injury. We investigated whether xenon, administered prior to hypothermia or simultaneously with hypothermia, also protects the rat heart from reperfusion injury.


METHODS
Anaesthetized rats (chloralose, ketamine, diazepam) were randomly allocated to five groups and subjected to 25 min coronary artery occlusion, followed by 120 min reperfusion. At the onset of reperfusion, controls received no intervention and inhaled oxygen in air with an inspired oxygen fraction of 0.8 (Con80). Further groups received either 1 h of mild hypothermia of 34 degrees C (Hypo34) or 30 min of xenon 20% (Xe20). Additional groups received xenon 20% and hypothermia 34 degrees C simultaneously (Xe20 + Hypo34) or in succession (Xe20-->Hypo34). Infarct sizes were assessed by triphenyltetrazolium chloride staining.


RESULTS
The combination of xenon 20% and hypothermia 34 degrees C significantly reduced infarct size [Xe20 + Hypo34: 55(22)%, mean (SD)] compared with control [Con80: 76(12)%, P = 0.03]. Xenon and hypothermia in succession produced no infarct size reduction.


CONCLUSIONS
The combination of xenon 20% and hypothermia of 34 degrees C, applied during early reperfusion, reduces infarct size in the rat heart in vivo.
Schwiebert
Christian
C
Department of Anaesthesiology, University of Amsterdam, Amsterdam, The Netherlands.
Huhn
Ragnar
R
Heinen
Andre
A
Weber
Nina C
NC
Hollmann
Markus W
MW
Schlack
Wolfgang
W
Preckel
Benedikt
B
D000818:Animals; D003131:Combined Modality Therapy / Q000379:methods; D006321:Heart / Q000187:drug effects / Q000503:physiopathology; D007036:Hypothermia, Induced / Q000379:methods*; D008297:Male; D015428:Myocardial Reperfusion Injury / Q000188:drug therapy / Q000503:physiopathology / Q000517:prevention & control*; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors; D014978:Xenon / Q000008:administration & dosage*
D014978:Xenon