Molecular mechanism on the maturation of tissue oxygen supply system

组织供氧系统的成熟是组织损伤或血管阻塞后组织供氧的重要问题。鞘氨醇1-磷酸，S1P是一种来源于血小板的脂质介质，可能通过其G蛋白偶联的S1P1受体参与血管生成和成熟。我们研究了ROS是否影响S1P1受体的表达。结果表明，ROS似乎参与了诱导，然而，我们现在必须解决诱导机制。高盐负荷4周可增加DAHL盐敏感大鼠尿H_2O_2排泄量、肾皮质NADPH依赖的超氧化物歧化酶生成活性、尿8-异前列腺素和血栓素B_2排泄量，减少血浆NO终末产物的排泄，这一作用可被L-精氨酸拮抗。逆转录-聚合酶链式反应检测肾皮质NADPH氧化酶亚单位gp91Phox和p47Phox基因表达增加，口服L精氨酸可拮抗这一作用。Western印迹结果表明，高盐胁迫增加了总匀浆和膜部分的gp9lphx蛋白，这一作用可被L精氨酸拮抗。高盐胁迫使P47Phox蛋白显著增加，L-精氨酸仅在膜部分有明显的拮抗作用。这些结果表明，高盐负荷导致DS大鼠肾皮质中有效的L精氨酸缺乏一氧化氮合酶，并诱导NADPH氧化酶激活，而补充L精氨酸可拮抗这一作用。DS大鼠肾皮质中超氧化物的产生将加速钠重吸收和高血压，因为NO抑制了皮质集合管的钠重吸收，而超氧化物迅速消除了NO。

Maturation of tissue oxygen supply system is an important issue to supply oxygen to tissues after tissue injury or vascular obstruction. Sphingosine 1-Phosphate, S1P is a lipid mediator derived from platelets and is supposed to be involved in the angiogenesis and its maturation through its G-protein-coupled S1P1 receptor. We examined whether ROS affects S1P1 receptor expression. The results suggest ROS seems to be involved, however, we must now resolve the induction mechanism. The other studies concerning ROS and pathophysiologic state we did is as follows ; We detected that high salt loading for 4 weeks increased excretion of H_2O_2 in urine of Dahl salt sensitive rats, NADPH-dependent superoxide producing activity in enal cortex, urinary 8-isoprostane and thromboxane B_2 excretion, and decreased plasma NO end products, which were counteracted by L-arginine supplement. We examined an increase in the expressions of NADPH oxidase subunits, gp91phox and p47phox, mRNA abundance with RT-PCR in renal cortex, which was counteracted with oral L-arginine supplement. Western blot revealed that high-salt loading increased gp9lphox protein, which was counteracted by L-arginine supplement both in the total homogenates and in the membrane fractions. High-salt loading powerfully increased p47phox protein, which was distinctly counteracted by L-arginine supplement only in the membrane fractions. These results disclosed that high salt loading causes a deficiency in available L-arginine for NO sythases and induces NADPH oxidase activation in the renal cortex of DS rats, which were counteracted by L-arginine supplement. Superoxide production in the renal cortex of DS rats will accelerate sodium reabsorption and hypertension, since NO inhibits sodium reabsorption in the cortical collecting duct and superoxide rapidly eliminates NO.