Hamilton S D, Pardue H L
Clin Chem. 1984 Feb;30(2):226-9.
We report conditions and characteristics of a new kinetic method for measuring lactate. Using a multiple linear regression method, we fit data for absorbance and for rate of change of absorbance to a modified rate form of the Michaelis-Menten equation. The principal objective of the fitting process is to compute the total absorbance change, delta A infinity, that would be measured if the reaction were monitored from the point of mixing to equilibrium. For data collected at 1-s intervals from 5 to 200 s, the fitting process gives values of delta A infinity that vary linearly with lactate concentration from 10.6 to 180 mumol/L in the reaction cell after 150-fold dilution of samples. For a range of enzyme activities that produced a 20% change in the initial rate, the regression-kinetic treatment yielded results with no detectable systematic error. The mean within-day CV was 2.1% for an average concentration of 14.4 mmol/L; the day-to-day CV was 5.2% for 3.90 mmol/L. For 25 samples of canine plasma with lactate concentrations from 2 to 26 mmol/L, comparison of results obtained with the regression-kinetic method (y) with results obtained with a commercially available equilibrium method (x) gave a least-squares equation of y = 1.01x - 10 mumol/L.
我们报告了一种测量乳酸的新动力学方法的条件和特性。使用多元线性回归方法，我们将吸光度数据和吸光度变化率数据拟合到米氏方程的修正速率形式。拟合过程的主要目标是计算如果从混合点到平衡监测反应将会测量到的总吸光度变化，即ΔA∞。对于在5至200秒内以1秒间隔收集的数据，拟合过程给出的ΔA∞值在样品经150倍稀释后，在反应池中与10.6至180μmol/L的乳酸浓度呈线性变化。对于一系列使初始速率产生20%变化的酶活性，回归动力学处理得到的结果没有可检测到的系统误差。平均浓度为14.4 mmol/L时，日内CV均值为2.1%；浓度为3.90 mmol/L时，日间CV为5.2%。对于25份乳酸浓度在2至26 mmol/L之间的犬血浆样本，将回归动力学方法得到的结果（y）与市售平衡方法得到的结果（x）进行比较，得到最小二乘方程y = 1.01x - 10μmol/L。
