McDonagh P F, Niven A T, Roberts D
Microvasc Res. 1984 Sep;28(2):180-96. doi: 10.1016/0026-2862(84)90016-5.
An isolated, arrested rat heart preparation which has coronary tone similar to that found in vivo and allows direct visualization of the coronary microcirculation is described. The rat hearts are perfused in situ prior to isolation. This procedure obviates any ischemic ischemic damage to the heart. The perfusate used is a modified Krebs solution with 40 mM potassium, 2 g% albumin, and washed red cells (20% HCT). To directly view the coronary microcirculation, a fluorescent albumin conjugate is added to the cell-rich perfusate. The epicardial microvessels are illuminated and observed with a fluorescence microscope. It was found that the control intercapillary distance in this model (33 microns) was almost twice that reported by other investigators for working hearts and suggested a 60-70% coronary capillary reserve in the arrested heart. The calcium blocker nisoldipine (Miles Laboratories) caused a dose-dependent coronary vasodilation using either a constant-flow or constant-pressure protocol. The coronary reactivity of this preparation to nisoldipine was 50 times greater than reported for isolated hearts perfused with cell-free Krebs solution. Further, the preparation vasodilated in a dose-dependent manner to histamine, but histamine did not cause a significant increase in coronary permeability to macromolecules. This model is appropriate for both physiologic and pharmacologic studies. It is particularly well suited for determining the direct effects of an intervention on coronary tone and the coronary microcirculation.
本文描述了一种离体、停搏的大鼠心脏标本，其冠状动脉张力与在体情况相似，且能直接观察冠状动脉微循环。在分离大鼠心脏之前，先对其进行原位灌注。此操作可避免心脏受到任何缺血性损伤。所用灌注液是一种改良的 Krebs 溶液，含 40 mM 钾、2 g%白蛋白和洗涤过的红细胞（血细胞比容 20%）。为了直接观察冠状动脉微循环，向富含细胞的灌注液中加入了一种荧光白蛋白偶联物。用荧光显微镜照亮并观察心外膜微血管。结果发现，该模型中的对照毛细血管间距（33 微米）几乎是其他研究者报道的工作心脏的两倍，提示停搏心脏的冠状动脉毛细血管储备为 60 - 70%。钙通道阻滞剂尼索地平（迈尔斯实验室）采用恒流或恒压方案均可引起剂量依赖性的冠状动脉血管舒张。该标本对尼索地平的冠状动脉反应性比用无细胞 Krebs 溶液灌注的离体心脏报道的反应性大 50 倍。此外，该标本对组胺呈剂量依赖性血管舒张，但组胺并未导致冠状动脉对大分子的通透性显著增加。此模型适用于生理学和药理学研究。它特别适合用于确定干预措施对冠状动脉张力和冠状动脉微循环的直接影响。
