Robinson S P, Rodrigues L M, Griffiths J R, Stubbs M
CRC Biomedical Magnetic Resonance Research Group, Division of Biochemistry, St. George's Hospital Medical School, London, United Kingdom.
Neoplasia. 1999 Dec;1(6):537-43. doi: 10.1038/sj.neo.7900027.
The effects of hyperoxia (induced by host carbogen [95% oxygen/5% carbon dioxide breathing] and hypoxia (induced by host carbon monoxide [CO at 660 ppm] breathing) were compared by using noninvasive magnetic resonance (MR) methods to gain simultaneous information on blood flow/oxygenation and the bioenergetic status of rat Morris H9618a hepatomas. Both carbogen and CO breathing induced a 1.5- to 2-fold increase in signal intensity in blood oxygenation level dependent (BOLD) MR images. This was due to a decrease in deoxyhemoglobin (deoxyHb), which acts as an endogenous contrast agent, caused either by formation of oxyhemoglobin in the case of carbogen breathing, or carboxyhemoglobin with CO breathing. The results were confirmed by observation of similar changes in deoxyHb in arterial blood samples examined ex vivo after carbogen or CO breathing. There was no change in nucleoside triphosphates (NTP)/P(i) in either tumor or liver after CO breathing, whereas NTP/P(i) increased twofold in the hepatoma (but not in the liver) after carbogen breathing. No changes in tumor intracellular pH were seen after either treatment, whereas extracellular pH became more alkaline after CO breathing and more acid after carbogen breathing, respectively. This tumor type and the liver are unaffected by CO breathing at 660 ppm, which implies an adequate oxygen supply.
通过使用非侵入性磁共振（MR）方法，比较了高氧（由宿主吸入混合气[95%氧气/5%二氧化碳]诱导）和低氧（由宿主吸入一氧化碳[660 ppm CO]诱导）对大鼠Morris H9618a肝癌血流/氧合及生物能量状态的影响，以同时获取相关信息。吸入混合气和吸入CO均使血氧水平依赖（BOLD）MR图像中的信号强度增加了1.5至2倍。这是由于作为内源性造影剂的脱氧血红蛋白（deoxyHb）减少所致，吸入混合气时是因为形成了氧合血红蛋白，吸入CO时则是形成了羧基血红蛋白。在吸入混合气或CO后对离体动脉血样本中deoxyHb的类似变化进行观察，证实了该结果。吸入CO后，肿瘤和肝脏中的三磷酸核苷（NTP）/无机磷酸盐（P(i)）均无变化，而吸入混合气后肝癌中的NTP/P(i)增加了两倍（肝脏中未增加）。两种处理后肿瘤细胞内pH均无变化，而细胞外pH在吸入CO后变得更碱性，在吸入混合气后变得更酸性。这种肿瘤类型和肝脏不受660 ppm CO吸入的影响，这意味着有充足的氧气供应。
