摘要
目的评价硝酸甘油对局部心肌氧代谢和心肌收缩功能的影响。方法实验应用8只具有静息状态血流限制的左前降支或左回旋支近端狭窄的开胸犬。以二维超声心动图评价室壁增厚率(%WT),放射性微球定量心肌血流量(MBF),用磷猝熄法在体直接测定心肌组织氧压(tPO_2)。分别在静息和左冠脉主干内输注硝酸甘油(0.3～0.6mg·kg-1)状态下,进行二维超声检查、核素微球注射,以及tPO_2和心肌氧耗量(MVO_2,ml·min-1·100g-1)测定,MVO_2等于冠状动脉与冠状静脉氧浓度差乘以MBF,心肌氧输送能力等于冠状动脉氧浓度差乘以MBF。结果与静息状态相比,经左冠脉主干内输注硝酸甘油时,无论是正常灌注区抑或是缺血灌注区的MBF明显增加(P<0.05),同时伴有%WT明显增加(P<0.05)。正常和缺血灌注区的心肌氧输送能力明显增加(P<0.05),尽管缺血灌注区的MVO2有明显增加(P<0.05),但是缺血灌注区的tPO_2仍明显增高(P<0.05)。缺血区心肌tPO_2增加的程度明显大于MBF增加的程度。结论硝酸甘油可明显提高正常和缺血灌注区心肌氧浓度,提高缺血灌注区血氧的解离和释放,可能具有正性肌力效应。除了其直接血管效应之外,硝酸甘油还通过对心肌氧代谢和收缩功能的影响在心血管中发挥重要的调节作用。
Objective To investigate the effects of nitroglycerine （NTG） on myocardial oxygen metabolism and regional cardiac function in canine hearts with a stable systemic hemodynamics in situ. Methods Eight anesthetized open-chest dogs with flow-limited left anterior descending branch of the coronary artery or left circumflex artery （LCx） stenosis were studied. The percentage of ventricular wall thickening （%WT） was measured with quantitative two-dimensional echocardiography （2DE）, myocardial blood flow （MBF） with radiolabeled microspheres and tissue oxygen pressure （tPO2） with oxygen-dependent quenching of. phosphorescence. 2DE was performed and radiolabeled microspheres and Pd-porphyrin injected in the dogs at rest during intracoronary infusion of 0.3-0.6 mg· kg^-1·min^-1 of NTG. Myocardial oxygen consumption （MVO2, ml·min^-1· 100 g^-1） was calculated as the multiplication product between the arterio-venous oxygen content difference and MBF, and myocardial 02 delivery as the product between arterial oxygen content and MBF. Results As compared with the baseline, NTG increased %WT and MBF significantly in both normal and ischemic beds （P〈0.05）. There was a significant increase in MVO2during NTG infusion in the ischemic bed （P〈0.05） in comparison with that measured at rest. NTG, however, significantly increased the ability of myocardial 02 delivery in both normal and ischemic beds （P〈0.05）, therefore tPO2 was still higher in the ischemic bed during NTG infusion than that at rest （P〈0.05）. The percentage increment in tPO2 was significantly greater in the ischemic bed than percentage MBF increment. Conclusions NTG enhances myocardial oxygen concentration in normal and ischemic myocardium and may increase oxygen release to the ischemic myocardium in vivo. NTG may have a positive inotropic effect on regional cardiac function. In addition to direct effect on vascular tone, NTG plays important roles in the cardiovascular system by modulating myocardial oxygen metabolism and contractile function.
出处
《南方医科大学学报》
CAS
CSCD
北大核心
2007年第4期423-426,共4页
Journal of Southern Medical University
基金
国家"863"计划项目(2006AA02Z478)~~
关键词
硝酸甘油
心肌氧代谢
心肌收缩功能
nitroglycerine
myocardial oxygen metabolism
myocardial contractile function
