Biosynthesis and degradation of D-lactate and its physiological meaning in higher animal.

1. d -乳酸测定方法的建立：d -乳酸通过d -乳酸脱氢酶转化为丙酮酸。在反应溶液中加入联氨和nadh -再氧化体系以完成反应。将生成的丙酮酸转化为2-羟基-3-甲基喹啉(I)或2-羟基-6,7-二甲氧基-3-甲基喹啉（II），采用荧光检测高效液相色谱法测定。(1)的测定限为600 fmol，(2)的测定限为80 fmol。甲基乙二醛（MG）的生成：由MG生成l -乳酸。据报道，MG是由动物体内的几种化合物形成的。由于目前使用的MG测定方法不精确，我们用选择性灵敏的测定方法重新检查了这些MG形成路线。结果表明，MG主要由三磷酸酯形成。运动后血浆中d -乳酸及其相关化合物水平的变化：由于我们的实验发现MG与能量和葡萄糖代谢相关，因此我们测定了血液中d -乳酸及其相关代谢物。d -乳酸水平只比l -乳酸高两倍，没有l -乳酸多。血浆中MG含量下降，尤其是红细胞。运动后汗液和尿液中d -乳酸和MG含量没有变化。糖尿病和禁食大鼠血液和肝脏中d -乳酸及其相关化合物含量的变化：与正常组相比，糖尿病和禁食大鼠的磷酸果糖激酶活性没有改变，但丙酮酸激酶活性下降。糖尿病大鼠血d -乳酸升高至正常值的2倍，MG和丙酮酸降低。其l -乳酸水平变化较小。糖尿病大鼠肝脏中D-和l -乳酸含量升高，MG和丙酮酸含量下降。在饥饿大鼠的情况下，血液中d -乳酸和MG水平升高，而丙酮酸和l -乳酸水平降低。d -乳酸、MG和丙酮酸水平下降。

1. Establishment of the determination of D-lactate: D-Lactate was converted into pyruvate by D-lactate dehydrogenase. Hydrazine and a NADH-reoxidation-system were added to the reaction solution in order to complete the reaction. The formed pyruvate was converted into 2-hydroxy-3-methylquinoxaline (I) or 2-hydroxy-6,7-dimethoxy-3-methylquinoxaline (II), which were determined by HPLC with fluorescence detection. The determination limit was 600 fmol for (I) and 80 f mol for (II).2. Formation of methylglyoxal (MG): L-Lactate was formed from MG. It was reported that MG was formed from several compounds in animals. These MG formation routes were reexaminated by our selective and sensitive determination method, because MG-determination methods hitherto used were not exact. As result, MG was found to be formed mainly from triosephosphates.3. Changes in D-lactate and its related compound levels in blood plasma after exercise: Since MG was found to be correlated to energy and glucose metabolism by our experiments, D-lactate and its related metabolites in blood were determined. The D-lactate level was only about twice higher, not as much as L-lactate. The MG level, however, decreased in plasma, especially in red blood cells. D-Lactate and MG in: sweat and urine did not change after exercise.4. Changes in D-lactate and its related compound content in blood and liver of diabetic and fasted rats: Phosphofructokinase activity of diabetic and fasted rats was not altered compared to a normal group, but pyruvate kinase activity decreased. The D-Lactate level in blood of diabetic rats increased to the double of the normal value, but MG and pyruvate decreased. The change of its L-lactate level was small. The D- and L-Lactate contents in liver of diabetic rats rised but the MG and pyruvate levels fell. In the case of starved rats, the D-lactate and MG levels in blood were elevated but pyruvate and L-lactate were decreased. D-lactate, MG and pyruvate levels fell.