Glenny R W, Bernard S, Robertson H T, Hlastala M P
Department of Medicine, University of Washington, Seattle, Washington 98195, USA.
J Appl Physiol (1985). 1999 Feb;86(2):623-32. doi: 10.1152/jappl.1999.86.2.623.
Original studies leading to the gravitational model of pulmonary blood flow and contemporary studies showing gravity-independent perfusion differ in the recent use of laboratory animals instead of humans. We explored the distribution of pulmonary blood flow in baboons because their anatomy, serial distribution of vascular resistances, and hemodynamic responses to hypoxia are similar to those of humans. Four baboons were anesthetized with ketamine, intubated, and mechanically ventilated. Different colors of fluorescent microspheres were given intravenously while the animals were in the supine, prone, upright (repeated), and head-down (repeated) postures. The animals were killed, and their lungs were excised, dried, and diced into approximately 2-cm3 pieces with the spatial coordinates recorded for each piece. Regional blood flow was determined for each posture from the fluorescent signals of each piece. Perfusion heterogeneity was greatest in the upright posture and least when prone. Using multiple-stepwise regression, we estimate that 7, 5, and 25% of perfusion heterogeneity is due to gravity in the supine, prone, and upright postures, respectively. Although important, gravity is not the predominant determinant of pulmonary perfusion heterogeneity in upright primates. Because of anatomic similarities, the same may be true for humans.
导致肺血流重力模型的原始研究以及显示与重力无关的灌注的当代研究，在近期对实验动物而非人类的使用上存在差异。我们研究了狒狒的肺血流分布，因为它们的解剖结构、血管阻力的连续分布以及对缺氧的血流动力学反应与人类相似。四只狒狒用氯胺酮麻醉，插管并进行机械通气。在动物处于仰卧、俯卧、直立（重复）和头低位（重复）姿势时静脉注射不同颜色的荧光微球。动物被处死，取出肺脏，干燥后切成约2立方厘米的小块，并记录每块的空间坐标。根据每块的荧光信号确定每种姿势下的局部血流。灌注不均匀性在直立姿势时最大，俯卧时最小。使用多元逐步回归分析，我们估计在仰卧、俯卧和直立姿势下，分别有7%、5%和25%的灌注不均匀性是由重力引起的。尽管重力很重要，但它并不是直立灵长类动物肺灌注不均匀性的主要决定因素。由于解剖结构相似，人类可能也是如此。
