Anaesthetics alter the magnitude of infarct limitation by ischaemic preconditioning.
OBJECTIVE
The aim was to determine whether three commonly used animal anaesthetics alter the magnitude of infarct limitation achieved with ischaemic preconditioning.


METHODS
Eighty four anaesthetised non-preconditioned and preconditioned open chest rabbits underwent a 30 min coronary occlusion followed by 3 h reperfusion. Ischaemic preconditioning was achieved with 5 min coronary occlusion beginning 15 min before the 30 min coronary occlusion. The anaesthetics studied were: pentobarbitone (30 mg.kg-1 intravenously +30-50 mg.kg-1.h-1 intravenously), isoflurane (1.5-2.5% end expiratory), and ketamine/xylazine (cocktail of 67 mg ketamine and 6.7 mg xylazine.ml-1, 1 ml.kg-1 intramuscularly +0.3-1.3 ml.kg-1.h-1 intramuscularly). Area at risk was delineated with ZnCdS particles and infarction assessed with tetrazolium.


RESULTS
There were no significant differences in area at risk, heart rate, arterial pressure, and temperature between non-preconditioned and preconditioned hearts. Although infarct size was not significantly different among non-preconditioned hearts for each anaesthetic regimen (p = NS), the magnitude of infarct limitation with preconditioning varied with the anaesthetic employed (decrease in infarct size from control values of 81%, 44%, and 33% for pentobarbitone, isoflurane and ketamine/xylazine, respectively, p = 0.0145 for comparison of the three magnitudes, two factor ANOVA).


CONCLUSIONS
Anaesthetic regimens affect the degree of infarct size limitation seen with ischaemic preconditioning.
Haessler
R
R
Department of Anesthesiology, Portland VA Medical Center, Oregon 97201-1034.
Kuzume
K
K
Chien
G L
GL
Wolff
R A
RA
Davis
R F
RF
Van Winkle
D M
DM
D000777:Anesthetics / Q000494:pharmacology*; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D003250:Constriction; D003331:Coronary Vessels; D006321:Heart / Q000187:drug effects*; D007530:Isoflurane / Q000494:pharmacology; D007649:Ketamine / Q000494:pharmacology; D009203:Myocardial Infarction / Q000097:blood / Q000473:pathology / Q000517:prevention & control*; D017202:Myocardial Ischemia / Q000097:blood / Q000378:metabolism*; D015425:Myocardial Reperfusion; D009206:Myocardium / Q000473:pathology; D010424:Pentobarbital / Q000494:pharmacology; D011817:Rabbits; D014693:Ventricular Fibrillation / Q000139:chemically induced
D000777:Anesthetics; D001786:Blood Glucose; D007649:Ketamine; D007530:Isoflurane; D010424:Pentobarbital