Changes in Myocardial Microcirculation Induced by Ischemia and Effects of Drugs on Them.

应用激光多普勒血流仪（LDF）测定麻醉开胸犬左心室搏动和停搏时心肌局部血流量（MBF）。将心外膜和心肌内血流探头放置在左前降支冠状动脉（LAD）灌注区，并连接到激光多普勒血流计（ALF 21），分别用于测量epi（EPI）和endothelial（ENDO）-MBF。在跳动的心脏中，EPI-和ENDO-MBF的LDF信号均显示逐搏变化。EPI-MBF峰值信号出现在收缩期的有6只，ENDO-MBF峰值信号出现在舒张期的有5只。硝酸甘油（20 μ g/kg i. v.），腺苷（0.5mg/kg i.（五）尽管用电磁流量计测量的LAD流量有明显变化，但LAD部分闭塞未能引起EPI和ENDO-MBF的显著变化。而在KC 1诱导的心脏停搏后，MBF信号几乎无一例外地下降到电零点水平。在电刺激迷走神经获得的长时间内，MBF和LAD流量均随着主动脉压（AoP）的降低而沿着线性下降。因此，这些舒张期血流中的每一个都显示出AoP的线性函数。然而，ENDO-MBF中通过回归线外推估计的零流量压力高于EPI-MBF。此外，ENDO/EPI流量比显着减少，在一个给定的压力低于70毫米汞柱的AoP。即使冠状动脉内输注腺苷消除了自动调节，也获得了类似的结果。这些数据表明，可能存在透壁不均匀的血管外压迫，作为组织血流在插管期间的背压。总之，本研究表明，LDF可以提供即时和连续的测量局部灌注在这两个epi和endofronts在原位。

Laser Doppler flowmetry (LDF) was applied to measure local myocardial blood flow (MBF) in the beating and arrested left ventricle of anesthetized open-chest dogs. An epicardial and an intramyocardial flow probe were placed in the left anterior descending coronary artery (LAD)-perfused region, and were connected to laser Doppler flowmeters (ALF21) for measurement of epi (EPI)- and endocardial (ENDO)-MBF, respectively. In the beating heart, LDF signals of both EPI- and ENDO-MBF showed beat-to-beat changes. The peak signals of EPI-MBF were observed during systole in 6 out 8 dogs, while those of ENDO-MBF were during diastole in 5 out of 8 dogs. Nitroglycerin (20 mug/kg i. v.), adenosine (0.5 mg/kg i. v.) or partial occlusion of LAD failed to produce significant changes in EPI- and ENDO-MBF, although apparent changes in LAD flow measured with an electromagnetic flowmeter were seen. After complete cardiac arrest induced by KC1, however, signals of MBF invariably fell almost to the electrical zero level. During a long diastole obtained by electrical stimulation of vagus, both MBFs as well as LAD flow linearly declined along with a decrease in aortic pressure (AoP). Thus, each of these diastolic flows showed a linear function of AoP. However, the pressure at zero flow estimated by extrapolation of the regression line in ENDO-MBF was higher than that in EPI-MBF. Moreover, ENDO/EPI flow ratio markedly lessened at a given pressure below 70 mmHg of AoP. Similar results were obtained even when autoregulation was abolished with intracoronary infusion of adenosine. These data suggest that there may be transmurally inhomogeneous extravascular compression as a back pressure to tissue blood flow during diastole. In conclusion, the present study demonstrated that LDF can provide instantaneous and continuous measurement of local perfusion in both the epi- and endocardium in situ.