急性缺氧兔心肌区域血流量的变化及一氧化氮和腺苷的调节作用

Changes of regional myocardial blood flow and the roles of nitric oxide and adenosine in regulation of myocardial blood flow in rabbits sustained acute hypoxia

目的探讨一氧化氮（NO）和腺苷在急性缺氧时心肌血流量调控中的作用。方法32只兔分为3组：Ⅰ组常氧对照组；Ⅱ组急性缺氧组；Ⅲ组急性缺氧＋NW-硝基-L-精氨酸（L－NA）组。后两组先在4000m高度停留30min，然后用戊巴比受纳麻醉。第Ⅲ组静脉滴入0．5％L－NA（0.3ml／min）20min。用放射性生物激球法测定心肌区域血流量和血管阻力。心肌组织中环磷酸鸟苷（cGMP）和腺苷含量分别用放免法和高效液相色谱仪测定。结果与对照组相比，急性缺氧组心肌区域血流量增加，心肌组织中cGMP和腺苷含量增高；急性缺氧＋L－NA组与急性缺氧组相比，心肌区域血流量降低，冠状血管阻力增加，心肌组织中cGMP含量降低，而腺苷含量则进一步增高。结论NO和腺苷均参与急性缺氧兔心肌血流量的调控。

Objective The aim was to investigate the role of nitric oxide(NO) and adenosine inregulation of myocardial blood flow (MBF) during acute hypoxia. Methods Thirty-two rabbits wererandomly divided into 3 groups: normoxia group (gr Ⅰ, n = 10),acute hypoxia group (gr Ⅱ,n= 10),andacute hypoxia + NW-nitro-L-arginine (L-NA) group (gr Ⅲ, n = 12 ), Group Ⅱ and group Ⅲ wereexposed to hypoxia of 4 000 m altitude for 30 min and then anesthetized with sodium pentobarbital. Togr Ⅲ, 0. 5% L-NA was given intravenously at a constant rate 0. 3 ml/min for 20 min,while to gr Ⅰ andgr Ⅱ normal saline was given instead. Regional myocardial blood flow and vascular resistance were measured using radiolabelled biological microspheres, myocardial cGMP and adenosine contents were determined by radioimmunoassay and high-performance liquid chromatography respectively. Results In grⅡ, left and right ventricular regional MBF , myocardial cGMP ana adenosine contents were significantly. increased as compared with those of gr Ⅰ, while in gr Ⅲ, the left and right ventricular MBF and the myocardial cGMP content were significantly reduced, whereas coronary vascular resistance and the myocardial adenosine content were significantly increased as compared with those of gr Ⅱ. Conclusion NOand adenosine were involved in the regulation of MBF in rabbits sustained acute hypoxia.