Uğurbil K, Merkle H, Robitaille P M, Hendrich K, Yoshiyama M, Path G, Zhang J, Tristani M, From A H, Bache R J
Department of Biochemistry, Gray Freshwater Biological Institute, University of Minnesota, Navarre 55392.
NMR Biomed. 1989 Dec;2(5-6):317-28. doi: 10.1002/nbm.1940020523.
Coronary stenosis results in transmurally non-uniform blood flow with the inner layers of the left ventricular wall typically suffering a more severe hypoperfusion relative to the outer layers. Coupled with numerous other transmural non-uniformities such as systolic tension development and oxygen needs, the heterogeneous blood flow distribution in the presence of coronary stenosis is expected to result in transmurally heterogeneous ischemia. All previous NMR spectroscopy studies of myocardial metabolism and bioenergetics under normal and ischemic conditions treated the organ as a homogeneous tissue. We have utilized spatially localized 31P NMR spectroscopy together with non-NMR measurements of regional blood flow to study the myocardium with transmural spatial differentiation under normal and flow-restricted conditions. 31P NMR and blood flow data obtained concurrently on each heart revealed that sustained coronary artery stenosis resulted in transmurally non-uniform ischemia which largely paralleled the hypoperfusion pattern. The reduction in creatine phosphate content (with consequent elevation of Pi) and hypoperfusion was tightly correlated in the subendocardium for flow rates less than approximately 0.7 mL/min per g wet myocardium. The high energy phosphate and Pi content of the epicardium, however, was responsive not only to the flow to this region but also to the extent of ischemia in the subendocardial layers. These results document the utility of localized NMR spectroscopy in physiologic research and suggest potential biomedical applications due to the tight correlation noted between alterations in blood flow and changes in the phosphorylated metabolite levels detected by 31P NMR.
冠状动脉狭窄导致跨壁血流不均匀，左心室壁内层相对于外层通常会遭受更严重的灌注不足。再加上许多其他跨壁不均匀性，如收缩期张力发展和氧气需求，冠状动脉狭窄情况下血流分布的异质性预计会导致跨壁异质性缺血。以往所有关于正常和缺血条件下心肌代谢和生物能学的核磁共振波谱研究都将该器官视为均匀组织。我们利用空间定位的31P核磁共振波谱以及区域血流的非核磁共振测量，在正常和血流受限条件下对具有跨壁空间差异的心肌进行研究。在每颗心脏上同时获得的31P核磁共振波谱和血流数据显示，持续性冠状动脉狭窄导致跨壁不均匀缺血，这在很大程度上与灌注不足模式平行。对于每克湿心肌流速小于约0.7 mL/min的情况，心内膜下肌酸磷酸含量的降低（以及随之而来的无机磷升高）与灌注不足密切相关。然而，心外膜的高能磷酸盐和无机磷含量不仅对该区域的血流有反应，而且对心内膜下层的缺血程度也有反应。这些结果证明了局部核磁共振波谱在生理学研究中的实用性，并表明由于血流变化与31P核磁共振检测到的磷酸化代谢物水平变化之间存在紧密相关性，因此具有潜在的生物医学应用价值。
