Bauer R, Bergmann R, Walter B, Brust P, Zwiener U, Johannsen B
Institute of Pathophysiology, Friedrich Schiller University, Jena, Germany.
Brain Res Dev Brain Res. 1999 Jan 11;112(1):89-98. doi: 10.1016/s0165-3806(98)00167-9.
The relationship between regional parenchymal cerebral blood volume (CBV), regional cerebral blood flow (CBF) and the calculated mean transit time (MTT) was investigated in 14 newborn piglets. The effects of combined hypoxic hypoxia (PaO2 = 32 +/- 5 mm Hg) and hypercapnia (paCO2 = 68 +/- 5 mm Hg) were measured in seven animals. Remaining animals served as the control group. During baseline conditions the highest CBF and CVB values were found in the lower brainstem and cerebellum, whereas white matter exhibited the lowest values (p < 0.05). MTT was prolonged within the cerebral cortex (2.34 +/- 0.42 s-1) compared with the thalamic MTT (1.53 +/- 0.38 s-1) (p < 0.05). Under moderate hypoxia/hypercapnia, a CBF increase to the forebrain (p < 0.05) resulted in an elevated brain oxygen delivery (p < 0.05) and so CMRO2 remained unchanged. Moreover, a moderate increase of CBV and a marked shortening of MTT occurred (p < 0.05). The CBV increase was higher in structures with lowest baseline values, i.e., thalamus (66% increase) and white matter (62% increase) (p < 0.05). MTT was between 22% of baseline in the lower brainstem and 49% in white matter (p < 0.05). We conclude that under normoxic and normocapnic conditions the newborn piglets exhibit a comparatively enlarged intraparenchymal CBV. Moderate hypoxia and hypercapnia induced a marked increase in cerebral blood flow which appears to be caused by an increased perfusion velocity, expressed by a strongly reduced mean transit time and by a concomitant CBV increase.
在14只新生仔猪中研究了局部脑实质血容量（CBV）、局部脑血流量（CBF）与计算得出的平均通过时间（MTT）之间的关系。对7只动物测量了低氧性缺氧（PaO2 = 32±5 mmHg）和高碳酸血症（paCO2 = 68±5 mmHg）联合作用的影响。其余动物作为对照组。在基线条件下，脑桥下部和小脑的CBF和CBV值最高，而白质的值最低（p < 0.05）。与丘脑的MTT（1.53±0.38 s-1）相比，大脑皮质内的MTT延长（2.34±0.42 s-1）（p < 0.05）。在中度缺氧/高碳酸血症情况下，前脑的CBF增加（p < 0.05）导致脑氧输送增加（p < 0.05），因此脑氧代谢率（CMRO2）保持不变。此外，CBV有适度增加，MTT明显缩短（p < 0.05）。基线值最低的结构，即丘脑（增加66%）和白质（增加62%）的CBV增加更高（p < 0.05）。MTT在脑桥下部为基线的22%，在白质中为49%（p < 0.05）。我们得出结论，在常氧和常碳酸血症条件下，新生仔猪表现出相对增大的脑实质内CBV。中度缺氧和高碳酸血症诱导脑血流量显著增加，这似乎是由灌注速度增加引起的，表现为平均通过时间大幅缩短以及伴随的CBV增加。
