Characterization of the pyruvate kinase which induces the low 2,3-DPG level of fetal rabbit red cells

The low 2,3-disphosphoglycerate (2,3-DPG) level of fetal rabbit red cells has been attributed previously to a very high pyruvate kinase (PK) activity. The present report shows that the high PK activity is associated with a distinct fetal isozyme. Fetal and adult rabbit red cell PK were characterized by the methods recommended by the International Committee for Standardization in Haematology. Fetal red cell PK differed from the adult enzyme by its greater thermostability, lower affinities for phosphoenolpyruvate and ADP, higher nucleotide specificity and lower ATP inhibition. Marked electrophoretic differences were not detected. Our results indicate that there is a developmental change in red cell PK isozyme expression in the rabbit. We do not know, however, if this change arises at the gene level or from cell-age dependent postsynthetic modifications of the enzyme. But in view of the role of PK in the control of the 2,3-DPG level and thereby of the oxygen affinity of red blood cells, we assume that the physiological significance of the PK isozyme change is akin to that of the switch from fetal to adult hemoglobin in other species.Abbreviations IU international unit - Hb hemoglobin - PK pyruvate kinase - 2,3-DPG 2,3-diphosphoglycerate - ATP adenosinetriphosphate - PEP phosphoenolpyruvate - F-1,6-diP fructose-1,6-diphosphate - ADP adenosine diphosphate - UDP uridine-diP - GDP guanosine-diP - CDP cytidine-diP - K_0.5 Michaelis constant     

泻浊纳气汤对慢性Ⅱ型呼吸衰竭患者2，3-二磷酸甘油酸的影响

RBC中的2,3-二磷酸甘油酸(2,3-DPG)是调节血红蛋白和氧亲和力的重要因素,在缺氧的情况下,人体即可通过RBC中的2,3-DPG浓度的改变来调节组织的获氧量。临床观察发现泻浊纳气汤(由石菖蒲、山萸肉、葶苈子组成)能提高2,3-DPG的含量,明显改善慢性呼吸衰竭患者缺氧和二氧化碳潴留的病理状态。     

7.5%高渗氯化钠溶液复苏失血性休克对红细胞能量代谢的影响

目的：观察小剂量高渗氯化钠（ＨＳ）复苏失血性休克时红细胞（ＲＢＣ）能量代谢的变化。方法：２０只健康家兔被随机分为三组，（甲组）正常血容量输注ＨＳ组；（乙组）休克输注ＮＳ复苏组；（丙组）休克输注ＨＳ复苏组。以ＲＢＣ内ＡＴＰ和２，３－ＤＰＧ水平作为ＲＢＣ能量代谢的指标。结果：休克后ＲＢＣ内ＡＴＰ和２，３－ＤＰＧ水平显著下降，应用小剂量ＨＳ复苏后两项指标均有所回升，在输注后１２０分钟有显著增高。结论：应用小剂量ＨＳ可使失血性休克后的ＲＢＣ能量代谢状态发生明显改善，这可能是促进ＨＳ有效复苏休克的重要因素。     

2,3-DPG levels in relation to red cell enzyme activities in rat fetuses and hypoxic newborns

We have measured in red cells from fetal and adult Sprague-Dawley and Wistar rats the activities of phosphofructokinase (PFK), pyruvate kinase (PK) and diphosphoglyceromutase (DPGM) as key enzymes in the regulation of 2,3-diphosphoglycerate (2,3-DPG) levels to gather information on the possible causes of the low concentration of 2,3-DPG in fetal red cells. The most striking differences were seen with regard to PK and DPGM activities. The activity of PK was ten times higher in fetal compared to adult red cells, whereas red cell DPGM activity was absent in fetuses and high in adults. In addition, we studied postnatal changes in red cell PK and DPGM activities as well as in the 2,3-DPG concentration in Sprague-Dawley rats. The concentration of 2,3-DPG and the activity of DPGM in red cells increased to almost the adult value within 2 and 4 weeks after birth, respectively, while the activity of PK decreased concomitantly. The postnatal changes occurred similarly, when newborn rats grew up under conditions of hypoxic hypoxia at 0.46 atm (pO₂=9.2 kPa). Our studies support the hypothesis that postnatal changes in 2,3-DPG levels are due to changes in the activity of certain glycolytic enzymes and that the switch from fetal-type to adult-type red cells follows a genetically determined time course.Part of the material presented in this paper has been communicated at the IXth International Berlin Symposium on Structure and Function of Erythroid Cells, 1980     

全血2，3－二磷酸甘油酸比色测定法

本文介绍了用磷酸甘油酸变位酶测定２，３－二磷酸甘油酸的比色法。探讨了该法的最适反应条件，最适ｐＨ７．５～７．６。线性范围可达６．０ｍｍｏｌ／Ｌ。三份不同浓度标本批内ＣＶ１．１％～２．１％，批间ＣＶ２．５％～３．９％。６０例南京地区健康成人２．３－二磷酸甘油酸含量为１．６～２．７ｍｍｏｌ／Ｌ，平均回收率９４％，与Ｓｉｇｍａ试剂盒比较测定结果无显著性差异（Ｐ＞０．０５），相关性良好，ｒ＝０．９８２。