Wagner Jens A, Abesser Marco, Harvey-White Judith, Ertl Georg
Department of Internal Medicine 1, Center of Cardiovascular Medicine, University of Würzburg, Würzburg, Germany.
J Cardiovasc Pharmacol. 2006 May;47(5):650-5. doi: 10.1097/01.fjc.0000211752.08949.eb.
Endocannabinoids have been implicated in protective effects in the heart and brain, but the mechanism of possible infarct-size-reducing effects remains controversial. Using a model of delayed preconditioning (PC), rats received the nitric oxide (NO) donor nitroglycerin (0.15 mg/h/kg) for 24 hours via transdermal application. Two days later, rat isolated perfused hearts were subjected to global, no-flow ischemia (20 min), and reperfusion (120 min). Cannabinoid receptor antagonists were given before no-flow throughout the protocol. Endocannabinoids were detected by liquid chromatography and mass spectrometry. NO-induced PC reduced the left ventricular infarct size from 40.9 +/- 3.9% to 27.5 +/- 3.8% (P < 0.05). Treatment with the specific CB1 cannabinoid receptor antagonist AM-251 (0.3 microM) prevented the protective effect of PC on infarct size (40.2 +/- 4.7%, P > 0.05 vs. controls). On the contrary, the specific CB2 receptor antagonist AM-630 (0.3 microM) did not alter infarct size (31.6 +/- 6.3%, P > 0.05 vs. PC alone). Recovery of left ventricular developed pressure and coronary flow was incomplete in control and NO-pretreated hearts and not consistently altered by cannabinoid receptor antagonists. PC increased the heart tissue content of the endocannabinoid 2-arachidonylglycerol (2-AG) from 4.6 +/- 1.0 nmol/g in controls to 12.0 +/- 2.1 nmol/g (P < 0.05). Tissue levels of the endocannabinoid arachidonylethanolamide (anandamide) remained unchanged (19.8 +/- 3.9 pmol/g vs. 19.5 +/- 4.8 pmol/g). 2-AG (1 microM) or its metabolically stable derivative noladinether (0.1 microM), given 30 minutes before ischemia/reperfusion in unpreconditioned hearts, mimicked the cardioprotective effects of PC and reduced infarct size. We conclude that delayed PC through transdermal nitroglycerin application increases the production of the endocannabinoid 2-AG which elicits protective effects against myocardial infarction via CB1 cannabinoid receptors which represents one new mechanism of NO-mediated PC.
内源性大麻素已被证实对心脏和大脑具有保护作用，但其可能的减小梗死面积的作用机制仍存在争议。采用延迟预处理（PC）模型，大鼠通过经皮给药接受一氧化氮（NO）供体硝酸甘油（0.15mg/h/kg），持续24小时。两天后，对大鼠离体灌注心脏进行全心无血流缺血（20分钟）和再灌注（120分钟）。在整个实验过程中，在无血流之前给予大麻素受体拮抗剂。通过液相色谱和质谱法检测内源性大麻素。NO诱导的PC使左心室梗死面积从40.9±3.9%降至27.5±3.8%（P<0.05）。用特异性CB1大麻素受体拮抗剂AM-251（0.3μM）处理可阻止PC对梗死面积的保护作用（40.2±4.7%，与对照组相比P>0.05）。相反，特异性CB2受体拮抗剂AM-630（0.3μM）并未改变梗死面积（31.6±6.3%，与单独PC组相比P>0.05）。在对照组和NO预处理的心脏中，左心室舒张末压和冠状动脉血流的恢复不完全，大麻素受体拮抗剂也未使其持续改变。PC使心脏组织内源性大麻素2-花生四烯酸甘油酯（2-AG）的含量从对照组的4.6±1.0nmol/g增加到12.0±2.1nmol/g（P<0.05）。内源性大麻素花生四烯酸乙醇胺（花生四烯酸酰胺）的组织水平保持不变（19.8±3.9pmol/g对19.5±4.8pmol/g）。在未预处理的心脏中，在缺血/再灌注前30分钟给予2-AG（1μM）或其代谢稳定的衍生物诺拉地嗪醚（0.1μM），可模拟PC的心脏保护作用并减小梗死面积。我们得出结论，通过经皮应用硝酸甘油进行延迟PC可增加内源性大麻素2-AG的产生，其通过CB1大麻素受体对心肌梗死产生保护作用，这代表了NO介导PC的一种新机制。
