Gamcsik M P, Constantinidis I, Glickson J D
Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
Cancer Res. 1991 Jul 1;51(13):3378-83.
The in vivo 14N nuclear magnetic resonance spectra of s.c. implanted murine radiation induced fibrosarcomas (RIF-1) display narrow resonances assignable to betaine and other trimethylamines and broad resonances due to amino acids and peptides. In 19 of the 41 tumors studied a distinct resonance from the ammonium ion is detectable. The accumulation of ammonium in the tumor to nuclear magnetic resonance detectable levels may result from glutaminolysis (a possible pathway for energy production in the tumor), from the degradation of peptides and proteins, or from the deamination of adenine nucleotides. Estimates of the tissue ammonium concentration were obtained from the in vivo tumor spectrum and the spectrum of the nonlabile trimethylamines in the perchloric acid extract. In the extract, the 14N resonances of betaine, carnitine, choline, phosphorylcholine, and glycerophosphorylcholine were resolved, and a relatively high level of tissue urea was observed. Spin-lattice relaxation times were obtained for the 14N nucleus of each of these metabolites in phosphate buffer.
皮下植入的小鼠辐射诱导纤维肉瘤（RIF-1）的体内14N核磁共振谱显示出可归因于甜菜碱和其他三甲胺的窄共振峰，以及由于氨基酸和肽产生的宽共振峰。在所研究的41个肿瘤中，有19个可检测到铵离子产生的明显共振峰。肿瘤中铵积累至核磁共振可检测水平可能源于谷氨酰胺分解代谢（肿瘤中一种可能的能量产生途径）、肽和蛋白质的降解或腺嘌呤核苷酸的脱氨基作用。通过体内肿瘤谱和高氯酸提取物中稳定三甲胺的谱图获得组织铵浓度的估计值。在提取物中，甜菜碱、肉碱、胆碱、磷酸胆碱和甘油磷酸胆碱的14N共振峰得到分辨，并且观察到组织尿素水平相对较高。在磷酸盐缓冲液中获得了这些代谢物中每一种的14N原子核的自旋晶格弛豫时间。
