کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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2760396 | 1150172 | 2009 | 6 صفحه PDF | دانلود رایگان |
ObjectivesBrief, repetitive administration of helium before prolonged coronary artery occlusion and reperfusion protects myocardium against infarction. Opioid receptors mediate the cardioprotective effects of ischemic pre- and postconditioning, but whether these receptors also play a role in helium preconditioning is unknown. The authors tested the hypotheses that opioid receptors mediate helium preconditioning and that morphine (a μ1-opioid receptor agonist with δ1-opioid agonist properties) lowers the threshold of cardioprotection produced by helium in vivo.DesignA randomized, prospective study.SettingA university research laboratory.ParticipantsMale New Zealand white rabbits.InterventionsRabbits (n = 56) were instrumented for the measurement of systemic hemodynamics and subjected to a 30-minute left anterior descending coronary artery (LAD) occlusion and 3 hours of reperfusion. In separate experimental groups, rabbits (n = 6 or 7 per group) received 0.9% saline (control), 1 or 3 cycles of 70% helium–30% oxygen administered for 5 minutes interspersed with 5 minutes of an air-oxygen mixture, morphine (0.1 mg/kg intravenously), or the nonselective opioid antagonist naloxone (6 mg/kg intravenously) before LAD occlusion. Other groups of rabbits received 3 cycles of helium or 1 cycle of helium plus morphine (0.1 mg/kg) in the absence or presence of naloxone (6 mg/kg) before ischemia and reperfusion. Statistical analysis of data was performed with analysis of variance for repeated measures followed by Bonferroni modification of the Student t test.Measurements and Main ResultsMyocardial infarct size was determined by using triphenyltetrazolium chloride staining and presented as a percentage of the left ventricular area at risk. Helium reduced myocardial infarct size in an exposure-related manner (36 ± 6 [p > 0.05] and 25% ± 4% [p < 0.05 v control] for 1 and 3 cycles of helium, respectively; data are mean ± standard deviation) compared with control (44% ± 7%). Morphine and naloxone alone did not affect infarct size (45 ± 2 and 40% ± 8%, respectively). The combination of 1 cycle of helium and morphine reduced infarct size (24% ± 5%, p < 0.05 v control) to an equivalent degree as 3 cycles of helium. Naloxone pretreatment abolished cardioprotection produced by 3 cycles of helium (47% ± 2%) and the combination of 1 cycle of helium plus morphine (45% ± 4%).ConclusionsThe results indicate that morphine lowers the threshold of helium preconditioning. Opioid receptors mediate helium preconditioning and its augmentation by morphine in vivo.
Journal: Journal of Cardiothoracic and Vascular Anesthesia - Volume 23, Issue 5, October 2009, Pages 619–624