Remifentanil limits infarct size but attenuates preconditioning-induced infarct limitation.
OBJECTIVE
We investigated the influence of the narcotic anesthetic remifentanil on irreversible myocardial ischemic injury.


METHODS
New Zealand White rabbits were anesthetized with propofol (0.7-1.8 mg.kg.min) and then subjected to 30 min regional myocardial ischemia and 3 h reperfusion (CON). Some animals also underwent ischemic preconditioning, elicited by either one (IP1) or two (IP2) cycles of 5 min ischemia and 5 min reperfusion, and/or remifentanil, administered either as a transient infusion mimicking the preconditioning protocol (RP2, 10 microg x kg x min) or as a continuous infusion (R, 3-10 microg x kg x min). Rabbits were randomly assigned to experimental groups. Infarct size was assessed with tetrazolium. Results are reported as mean+/-SD.


RESULTS
Non-preconditioned infarct size was approximately 50% of the area-at-risk (49.6+/-20.1% CON). Both one and two cycles of ischemic preconditioning markedly reduced infarct size (49.6+/-20.1% CON versus 18.6+/-8.6% IP and versus 7.5+/-7.6% IP2; both p<0.001). Preconditioning with remifentanil modestly reduced infarct size (49.6+/-20.1% CON versus 29.3+/-8.5% RP2; p<0.01). However, sustained administration of remifentanil did not provide protection (49.6+/-20.1% CON versus 43.9+/-16.2% R), and it attenuated the protection offered by preconditioning (49.6+/-20.1% CON versus 35.6+/-20.7% R+IP1, p=NS; and versus 14.5+/-14.5% R+IP2; p<0.05).


CONCLUSIONS
Transient pre-ischemic administration of remifentanil modestly reduces infarct size in propofol-anesthetized rabbits, but continuous administration of remifentanil increases the threshold for ischemic preconditioning-induced infarct limitation.
Kuzume
Koh
K
Research Service, Veterans Affairs Medical Center, Portland, OR, USA.
Kuzume
Kazuyo
K
Wolff
Roger A
RA
Chien
Grace L
GL
Van Winkle
Donna M
DM
D000777:Anesthetics / Q000627:therapeutic use*; D000818:Animals; D019157:Ischemic Preconditioning, Myocardial; D009203:Myocardial Infarction / Q000188:drug therapy* / Q000473:pathology; D010880:Piperidines / Q000627:therapeutic use*; D011817:Rabbits; D000077208:Remifentanil
D000777:Anesthetics; D010880:Piperidines; D000077208:Remifentanil