van Beek J H, Elzinga G
Laboratory for Physiology, Free University, Amsterdam, The Netherlands.
Pflugers Arch. 1987 Oct;410(3):263-71. doi: 10.1007/BF00580275.
Diffusional shunting of oxygen in the saline-perfused heart was studied by comparing the time course of the coronary venous concentrations of oxygen and an intravascular indicator following a simultaneous step-like change in their arterial concentrations. To this end 7 rabbit hearts were perfused according to Langendorff with Tyrode solution at a perfusion flow rate of 3.8 +/- 1.4 ml.min-1.g-1 (wet weight) at 37 degrees C. In the reference situation arterial (Pao2) and venous oxygen tensions (Pvo2) were about 610 and 290 mmHg, respectively. Step changes in Pao2 were made to a 60 mmHg lower level and back. Simultaneously the arterial concentration of albumin-bound indocyanine green, an intravascular indicator, was changed. No deflection in PvO2 was detected before the venous dye concentration changed. The venous dye concentration crossed 5% of its step amplitude 4 s after the arterial change, on average 2.3 s before Pvo2 crossed its 5% level. We conclude that shunt diffusion of oxygen from arterioles to venules and from arterial to venous ends of the capillary bed is negligible in saline-perfused hearts and thus cannot explain the high value of Pvo2 in these preparations.
通过比较氧和血管内指示剂的动脉浓度同时发生阶跃变化后冠状静脉中氧和血管内指示剂浓度随时间的变化过程，研究了生理盐水灌注心脏中氧的扩散性分流。为此，7只兔心脏按照Langendorff法在37℃下用台氏液灌注，灌注流速为3.8±1.4 ml·min⁻¹·g⁻¹（湿重）。在参考情况下，动脉血氧分压（Pao2）和静脉血氧分压（Pvo2）分别约为610和290 mmHg。将Pao2阶跃降低60 mmHg然后再恢复。同时，改变与白蛋白结合的血管内指示剂吲哚菁绿的动脉浓度。在静脉染料浓度改变之前未检测到PvO2的变化。动脉变化后4 s，静脉染料浓度达到其阶跃幅度的5%，平均比Pvo2达到其5%水平早2.3 s。我们得出结论，在生理盐水灌注的心脏中，从微动脉到微静脉以及从毛细血管床的动脉端到静脉端的氧分流扩散可忽略不计，因此不能解释这些制剂中Pvo2的高值。
