COMPLEMENT IN THE REGULATION OF TRANSCELLULAR SODIUM GRADIENT DURING ILLNESS

补体和细胞因子作为细胞内钠介质的作用 重症期间的能量积累和增加的能量需求将 与中心资助的其他成员合作研究 应用程序.本节中描述的实验基于 补体激活和异常细胞因子产生假说 促进和维持跨膜细胞中潜在的致命改变， 钠梯度必然影响能量代谢， cell.因此，补体激活、细胞因子产生和 自由基的发生变化：1）钠和水的分布 跨细胞膜; 2）细胞生物能量学;和3）细胞内 和细胞外pH值进行检查。在已建立的啮齿动物模型中， 脓毒症和缺血再灌注损伤，具体目的是：1） 确定补体激活和细胞因子加工如何影响钠 和水分分布、Na ~+-K ~+ ATP酶活性、pH值的关系 腓肠肌和肝脏; 2）检测补体和 细胞因子对跨膜钠梯度和继发性 高能磷酸盐代谢的变化;以及3） 补体活性和细胞因子分泌，作为严重程度的标志物 损伤，与磷酸肌酸利用和其他体内变化 作为能量供应变化标志的细胞能量状态指数 和细胞内的需求。这些关系将在 腓肠肌和正常大鼠水平和大腿（股 外侧肌）肌肉。钠的变化 和水分布将使用体内钠磁 共振光谱（MRS）和位移试剂 三亚乙基四胺六乙酸镝（III）和磷MRS，以及 MRS-可见水空间标记物二甲基甲基膦酸酯和 苯基膦酸酯。磷酸肌酸分解率将是 使用体内31 P-MRS磁化转移技术测量。 将用于了解机制的实验干预措施 观察到的变化包括内毒素的施用， 使用sCR 1的TNF和补体阻断。这些体内实验应 阐明细胞内钠含量增加的机制 在危重病期间，提高我们对 细胞生物能量学，并促进战略的发展， 改善脓毒症和缺血再灌注损伤的作用。

The role of complement and cytokines as mediators of intracellular sodium accumulation and increased energy demand during critical illness will be studied in collaboration with the other members of the center grant application. The experiments described in this section are based on the hypothesis that complement activation and abnormal cytokine production facilitate and maintain potentially lethal alterations in transmembrane sodium gradients that necessarily affect energy metabolism within the cell. Thus, the role of complement activation, cytokine production, and free radicals in the genesis changes in: 1) sodium and water distribution across the cell membrane; 2) cellular bioenergetics; and 3)intracellular and extracellular pH will be examined. In established rodent models of sepsis, and ischemia and reperfusion injury, the specific aims are to: 1) determine how complement activation and cytokine elaboration affect sodium and water distribution, Na+-K+ ATPase activity, and pH in the gastrocnemius muscle and liver; 2) examine the effect of complement and cytokine inhibition on the transmembrane sodium gradient and secondary changes in high energy phosphate metabolism; and 3) correlate changes in complement activity and cytokine elaboration, as markers of the severity of injury, with changes in phosphocreatine utilization and other in vivo indices of cellular energy state as markers of changes in energy supply and demand within the cell. These relationships will be explored in the gastrocnemius muscle and level of normal rats and in the thigh (vastus lateralis) muscle of normal, complement deficient mice. Changes in sodium and water distribution will be measured using in vivo sodium magnetic resonance spectroscopy (MRS) and the shift reagent triethylenetetraminehexaacetate dysprosium (III) and phosphorus MRS and the MRS-visible water space markers dimethylmethylphosphonate and phenylphosphonate respectively. Phosphocreatine breakdown rates will be measured using in vivo 31P-MRS magnetization transfer techniques. Experimental interventions that will be used to understand the mechanisms of the observed changes will include the administration of endotoxin and TNF and complement blockade using sCR1. These in vivo experiments should clarify the mechanisms by which intracellular sodium content increases during critical illness, improve our understanding of the regulation of cellular bioenergetics and facilitate the development of strategies to ameliorate the effects of sepsis and ischemia-reperfusion injury.