Dewhirst M W, Kimura H, Rehmus S W, Braun R D, Papahadjopoulos D, Hong K, Secomb T W
Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710, USA.
Br J Cancer Suppl. 1996 Jul;27:S247-51.
Two forms of hypoxia are thought to exist in tumours: (1) hypoxia caused by limitations of its diffusion (chronic hypoxia); and (2) hypoxia caused by changes in perfusion (acute hypoxia). Indirect information suggests the existence of perfusion-limited hypoxia, but there is no direct proof that fluctuations in blood flow can lead to hypoxia, nor is there any information regarding potential causes of fluctuant flow. In this study, we have begun to explore these questions using R3230AC tumours transplanted into rat dorsal-flap window chambers. Two types of fluctuant flow have been observed. The first type, usually confined to single vessels, is typified by instability of flow magnitude and direction, and total vascular stasis occurs, but only for a few seconds at a time (4% incidence). The second type of fluctuation occurs in groups of vessels and is cyclic, with cycle times ranging from 20-60 min. Total vascular stasis does not necessarily occur, but the fluctuations in red cell flux are accompanied by changes in vascular oxygen content, as measured by microelectrodes. Another source of chronic hypoxia has also been identified in these experiments. Nine per cent (9%) of vessels examined had plasma flow, but very low or absent red cell flux over periods of many minutes.
（1）由扩散受限引起的缺氧（慢性缺氧）；（2）由灌注变化引起的缺氧（急性缺氧）。间接信息提示存在灌注受限性缺氧，但尚无直接证据表明血流波动会导致缺氧，也没有关于血流波动潜在原因的任何信息。在本研究中，我们开始使用移植到大鼠背部皮瓣开窗室的R3230AC肿瘤来探索这些问题。观察到两种类型的血流波动。第一种类型通常局限于单个血管，其特征是血流大小和方向不稳定，且会出现完全血管停滞，但每次仅持续几秒（发生率为4%）。第二种类型的波动发生在成组血管中，呈周期性，周期时间为20 - 60分钟。不一定会出现完全血管停滞，但通过微电极测量发现，红细胞通量的波动伴随着血管氧含量的变化。在这些实验中还发现了慢性缺氧的另一个来源。所检查的血管中有9%存在血浆流动，但在数分钟时间内红细胞通量非常低或无红细胞通量。
