Thompson G N, Walter J H, Bresson J L, Ford G C, Lyonnet S L, Chalmers R A, Saudubray J M, Leonard J V, Halliday D
Section of Perinatal and Child Health, Clinical Research Centre, Harrow, UK.
Metabolism. 1990 Nov;39(11):1133-7. doi: 10.1016/0026-0495(90)90084-p.
Amino acids are widely regarded as the most important sources of propionate in disorders of propionate metabolism. Propionate production was measured in the fasting state by continuous infusion of sodium [1-13C]propionate in three children with methylmalonic acidemia (MMA) and three with propionic acidemia (PA). The contribution of isoleucine, valine, threonine, and methionine catabolism to total propionate production was estimated by extrapolation from the hydroxylation of phenylalanine determined by a continuous-infusion [2H5]phenylalanine technique. The contribution of gut bacterial propionate production was determined by measuring total propionate production before and after treatment with oral metronidazole (10 to 20 mg/kg/d for 1 week). Amino acid catabolism accounted for a mean of 51.7% (range, 24.5% to 66.4%) of total propionate production. The mean decrease in propionate production after metronidazole was 22.2% +/- 8.5 (P less than .02); this percentage is likely to represent the minimum propionate production attributable to gut bacteria. Approximately 30% of total propionate production was unaccounted for, and is likely to arise primarily from odd-chain fatty acid catabolism in the fasting state. These results indicate that sources of propionate other than from protein catabolism are important in disorders of propionate metabolism, and explain the generally disappointing response to dietary protein restriction.
在丙酸代谢紊乱中，氨基酸被广泛认为是丙酸的最重要来源。通过对三名甲基丙二酸血症（MMA）患儿和三名丙酸血症（PA）患儿持续输注[1-13C]丙酸钠来测定空腹状态下的丙酸生成量。通过连续输注[2H5]苯丙氨酸技术测定苯丙氨酸羟化作用，并据此推断异亮氨酸、缬氨酸、苏氨酸和蛋氨酸分解代谢对总丙酸生成的贡献。通过测量口服甲硝唑（10至20mg/kg/d，持续1周）治疗前后的总丙酸生成量来确定肠道细菌产生丙酸的贡献。氨基酸分解代谢平均占总丙酸生成量的51.7%（范围为24.5%至66.4%）。甲硝唑治疗后丙酸生成量的平均下降幅度为22.2%±8.5（P<0.02）；该百分比可能代表肠道细菌产生的最低丙酸量。总丙酸生成量中约30%无法解释，可能主要来自空腹状态下奇数链脂肪酸的分解代谢。这些结果表明，除蛋白质分解代谢外，丙酸的其他来源在丙酸代谢紊乱中很重要，并解释了对饮食蛋白质限制的总体反应通常令人失望的原因。
