The cardioprotective effect of dexmedetomidine on global ischaemia in isolated rat hearts.
OBJECTIVE
Dexmedetomidine is a highly specific and selective alpha-2 adrenergic agonist that is now widely used in the intensive care setting. Many intensive care unit (ICU) patients are at risk of respiratory or cardiac arrest. This study was conducted to determine whether dexmedetomidine exhibits a cardioprotective effect on global ischaemia and subsequent myocardial infarction.


METHODS
Isolated rat hearts were subjected to 30 min of global ischaemia followed by 120 min reperfusion, with administration of 0, 1 and 10nM dexmedetomidine during the pre-ischaemic period (n=7 each group). Secondly, 1 microM yohimbine, an alpha-2 antagonist, was given during the pre-ischaemic period, alone or in combination with 10 nM dexmedetomidine (n=7 each group).


RESULTS
Dexmedetomidine administration reduced coronary flow significantly (103.6+/-4.7%, 77.9+/-3.7, 63.7+/-6.1%, of the baseline values for 0, 1 and 10 nM dexmedetomidine, respectively), and yohimbine administration reversed this effect (88.0+/-2.2%). Dexmedetomidine improved the infarct size at each concentration (45.3+/-3.6, 30.2+/-3.3, and 21.2+/-2.3% of the total left ventricular mass for 0, 1, and 10nM dexmedetomidine, respectively), which was also reversed by yohimbine (43.6+/-1.4%).


CONCLUSIONS
Dexmedetomidine exhibited a cardioprotective effect on global ischaemia in the isolated rat heart model, which was mediated by alpha-2 adrenergic stimulation.
Okada
Hisako
H
Department of Anaesthesiology and Intensive Care, Hamamatsu University School of Medicine, 1-20-1, Handayama, Hamamatsu, Shizuoka 431-3192, Japan. okadah@hama-med.ac.jp
Kurita
Tadayoshi
T
Mochizuki
Toshiaki
T
Morita
Koji
K
Sato
Shigehito
S
D000316:Adrenergic alpha-Agonists / Q000627:therapeutic use*; D000818:Animals; D003326:Coronary Circulation / Q000187:drug effects; D020927:Dexmedetomidine / Q000627:therapeutic use*; D004195:Disease Models, Animal; D006323:Heart Arrest / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D008297:Male; D009203:Myocardial Infarction / Q000150:complications / Q000188:drug therapy / Q000503:physiopathology; D015428:Myocardial Reperfusion Injury / Q000150:complications / Q000188:drug therapy* / Q000503:physiopathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D016896:Treatment Outcome; D016277:Ventricular Function, Left / Q000187:drug effects
D000316:Adrenergic alpha-Agonists; D020927:Dexmedetomidine