甜菜碱在提高血清乳酸脱氢酶活性稳定性中的作用

Role of betaine on the stability of serum lactate dehydrogenase

目的探讨不同浓度甜菜碱在不同保存温度(2~8℃、-20℃)下对血清乳酸脱氢酶(LDH)的稳定作用。方法将5 mol/L甜菜碱按不同比例加入血清样本中:第1组样本中不添加甜菜碱,第2~5组样本中甜菜碱与样本的比例(V∶V)分别为9∶1、8∶2、7.5∶2.5、6∶4,甜菜碱浓度为0.5~1.25 mol/L。所有血清样本在保存前先进行LDH总活性检测和LDH同工酶电泳分析,以该检测结果作为基线值,然后分别在2~8℃和-20℃保存不同时间后,检测LDH总活性及同工酶百分比,计算其与基线值的差异。结果第2~4组血清样本的LDH总活性回收率为98.36%~101.41%,第5组血清样本为95.16%~103.48%,有1份血清样本的偏移高于卫生行业标准WS/T 403—2012规定的偏差(4.0%)。2~8℃保存30 d,第1组血清样本LDH总活性仅为基线值的52.31%~59.95%,第2~4组血清样本LDH总活性是基线值的98.54%~101.64%,结果均较稳定。-20℃保存21 d,第1组血清样本LDH总活性是基线值的88.78%~91.57%,第2~4组血清样本LDH总活性仅为基线值的56.14%~65.34%。-20℃保存30 d,LDH同工酶中LDH1、LDH2比例升高,LDH3比例接近基线值,LDH4、LDH5比例为0。结论2~8℃条件下,浓度为0.5~1.25 mol/L的甜菜碱至少可稳定血清LDH总活性30 d。血清样本于-20℃保存,LDH不稳定。

Objective To study the role of different concentrations of betaine on serum lactate dehydrogenase(LDH)stability at different storage temperatures(2-8℃,-20℃).Methods The 5 mol/L betaine was added to serum samples at different ratios.No betaine was added to the samples in group 1.The ratios of betaine to sample(V∶V)were 9∶1,8∶2,7.5∶2.5 and 6∶4 for the samples in groups 2 to 5,respectively.Betaine concentration was 0.5-1.25 mol/L.All serum samples were determined for total LDH activity and LDH isoenzyme electrophoresis analysis before storage,and the results of this assay were used as baseline values.The total LDH activity and the percentage of isoenzymes were determined after storage at 2-8℃and-20℃for different times,respectively,and the differences from the baseline values were calculated.Results The recoveries of total LDH activity for serum samples in groups 2 to 4 ranged from 98.36%to 101.41%,and 95.16%-103.48%for serum samples in group 5.Among them,1 serum sample had an offset higher than the deviation specified in the Chinese health industry standard WS/T 403-2012(4.0%).Under 2-8℃storage for 30 d,the total LDH activity of serum samples in group 1 was 52.31%-59.95%of the baseline value.The total LDH activities of serum samples in groups 2 to 4 were 98.54%-101.64%of the baseline value,and the results were stable.The total LDH activity of serum samples in group 1 was 88.78%-91.57%of the baseline value when stored at-20℃for 21 d.The total LDH activities of serum samples in groups 2 to 4 were 56.14%-65.34%of the baseline value.The proportions of LDH1 and LDH2 among LDH isoenzymes were increased,the proportion of LDH3 was close to the baseline value,and the proportions of LDH4 and LDH5 were 0 when stored at-20℃for 30 d.Conclusions At 2-8℃,0.5-1.25 mol/L betaine stabilizes total serum LDH activity for at least 30 d.Serum LDH is unstable when stored at-20℃.