Kiel J W, Shepherd A P
Department of Physiology, University of Texas Health Science Center, San Antonio 78284.
Am J Physiol. 1989 Feb;256(2 Pt 2):H472-7. doi: 10.1152/ajpheart.1989.256.2.H472.
To determine whether an optimal hematocrit exists at which gastric tissue is maximally oxygenated, chambered segments of resting canine stomach were perfused at a constant pressure while hematocrit was decreased in steps from 60 to 10%. The two groups of animals used were a control group and a second group given pentagastrin to elevate metabolic activity. Total blood flow was inversely related to hematocrit in both the control and pentagastrin-treated animals, and arteriovenous oxygen difference was directly related to hematocrit. Consequently, the relationship between gastric oxygen consumption and hematocrit was parabolic in both groups. Therefore, the oxygen uptake vs. hematocrit data from each experiment were fit to a quadratic equation that was used to calculate the maximal oxygen uptake and the optimal hematocrit for each preparation. Both the maximum oxygen uptake and the optimal hematocrit in the pentagastrin-treated group (2.1 +/- 0.4 ml.min-1.100 g-1 and 45.7 +/- 1.4%, respectively) were significantly greater than in the control group (1.5 +/- 0.4 ml.min-1.100 g-1 and 38.2 +/- 0.7%, respectively). We conclude that an optimal hematocrit exists for the oxygenation of gastric tissue and that it is within the normal hematocrit range under resting conditions. However, the optimal hematocrit is slightly higher than normal during periods of increased metabolic activity.
为了确定是否存在一个能使胃组织获得最大氧合的最佳血细胞比容，在恒压条件下对处于静息状态的犬类胃的分腔节段进行灌注，同时将血细胞比容从60%逐级降至10%。所使用的两组动物，一组为对照组，另一组给予五肽胃泌素以提高代谢活性。在对照组和五肽胃泌素处理组动物中，总血流量均与血细胞比容呈负相关，动静脉氧差与血细胞比容呈正相关。因此，两组中胃耗氧量与血细胞比容之间的关系均呈抛物线形。所以，将每个实验中氧摄取量与血细胞比容的数据拟合成一个二次方程，用于计算每种制剂的最大氧摄取量和最佳血细胞比容。五肽胃泌素处理组的最大氧摄取量和最佳血细胞比容（分别为2.1±0.4 ml·min⁻¹·100 g⁻¹和45.7±1.4%）均显著高于对照组（分别为1.5±0.4 ml·min⁻¹·100 g⁻¹和38.2±0.7%）。我们得出结论，胃组织氧合存在一个最佳血细胞比容，在静息条件下它处于正常血细胞比容范围内。然而，在代谢活动增加期间，最佳血细胞比容略高于正常水平。
