Ng C E, McGovern K A, Wehrle J P, Glickson J D
Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287.
Magn Reson Med. 1992 Oct;27(2):296-309. doi: 10.1002/mrm.1910270209.
In order to examine the mechanisms underlying radiation-induced changes in phosphorus metabolite levels observed in RIF-1 tumors in vivo, RIF-1 cells in culture were perfused for up to 70 h following gamma-irradiation with 0-25 Gy and monitored continuously by 31P NMR spectroscopy at 8.5 T. Cells immobilized in the sample volume by incorporation into calcium alginate beads were bioenergetically stable, but did not replicate at the cell density used. Following an initial increase in PCr and NTP, which occurred in both control and irradiated cells, a dramatic decline in high-energy phosphates was detected beginning 24-30 h after irradiation with 15 or 25 Gy. In contrast, unirradiated cells or cells treated with 10 Gy remained metabolically stable for up to 72 h. The metabolic changes induced by irradiation of the cultured cells, which reflected cell death and lysis, were distinctly different from those observed in RIF-1 tumors in vivo during the same postirradiation time interval--an increase in high-energy relative to low-energy phosphates. This suggests that the spectral changes in vivo do not result from direct modification of cellular energy metabolism by radiation injury.
为了研究在体内RIF-1肿瘤中观察到的辐射诱导的磷代谢物水平变化的潜在机制，用0-25 Gy的γ射线照射培养的RIF-1细胞，持续灌注长达70小时，并在8.5 T下通过31P NMR光谱进行连续监测。通过掺入海藻酸钙珠固定在样品体积中的细胞在生物能量上是稳定的，但在所使用的细胞密度下不复制。在对照细胞和受辐照细胞中均出现的磷酸肌酸（PCr）和核苷三磷酸（NTP）最初增加之后，在用15或25 Gy照射后24-30小时开始检测到高能磷酸盐急剧下降。相比之下，未辐照的细胞或用10 Gy处理的细胞在长达72小时内保持代谢稳定。培养细胞受辐照诱导的代谢变化反映了细胞死亡和裂解，与在相同辐照后时间间隔内在体内RIF-1肿瘤中观察到的变化明显不同——高能磷酸盐相对于低能磷酸盐增加。这表明体内的光谱变化不是由辐射损伤对细胞能量代谢的直接修饰引起的。
