van Beek J H, Bouma P, Westerhof N
Laboratory for Physiology, Free University, Amsterdam, The Netherlands.
Pflugers Arch. 1989 May;414(1):82-8. doi: 10.1007/BF00585630.
In experiments reported in the literature, oxygen uptake in saline-perfused heart decreased after small reductions in arterial O2 concentration (CaO2) at constant perfusion flow. This may have resulted from the decrease in O2 supply, but may also have been due to decreased O2 demand caused by reduced perfusion pressure following hypoxic vasodilation (garden hose effect). We tested both possibilities in 8 isolated rabbit hearts, perfused with Tyrode solution at 37 degrees C, perfusion pressure 94 +/- 4 mm Hg (mean +/- SD). Vasodilation with 10 microM adenosine in the perfusate prevented changes in perfusion pressure during hypoxia. Oxygen uptake decreased significantly by 5.8 +/- 2.1% for a 10% decrease in CaO2 at constant flow, and by 4.4 +/- 1.8% per 10% decrease in flow at constant CaO2. In both cases a 10% reduction in oxygen supply was applied and the decrease in oxygen uptake was not significantly different. The decrease in perfusion pressure during flow reduction did therefore not cause a detectable decrease in oxygen consumption via the garden hose effect in addition to the decrease caused by reduced oxygen supply. The data show that oxygen uptake in saline-perfused rabbit heart, at 37 degrees C, is limited by O2 supply.
在文献报道的实验中，在恒定灌注流量下，当动脉血氧浓度（CaO2）稍有降低后，生理盐水灌注心脏的氧摄取量会下降。这可能是由于氧供应减少所致，但也可能是由于缺氧性血管舒张后灌注压降低引起的氧需求减少（花园软管效应）。我们在8个离体兔心脏中测试了这两种可能性，这些心脏在37℃下用台氏液灌注，灌注压为94±4 mmHg（平均值±标准差）。在灌注液中加入10μM腺苷进行血管舒张可防止缺氧期间灌注压的变化。在恒定流量下，CaO2降低10%时，氧摄取量显著下降5.8±2.1%；在恒定CaO2下，流量每降低10%，氧摄取量下降4.4±1.8%。在这两种情况下，均使氧供应减少10%，且氧摄取量的下降无显著差异。因此，流量降低期间灌注压的下降，除了因氧供应减少导致的下降外，并未通过花园软管效应引起可检测到的氧消耗下降。数据表明，在37℃下，生理盐水灌注兔心脏的氧摄取受氧供应的限制。
