INTESTINAL PROTEIN METABOLISM IN SEPSIS

蛋白质合成是肠道的一项重要功能，无论是从蛋白质合成还是从蛋白质合成， 定量和定性的观点。 该项目的目的是 确定脓毒症对肠道蛋白质代谢、合成的影响 肠肽的释放，肠上皮细胞的增殖和迁移 rates. 我们还将检验TNF、IL-1和IL-6调节 脓毒症时肠道蛋白质代谢。 最后，我们将研究 谷氨酰胺对肠上皮细胞蛋白质合成影响 对照组和脓毒症大鼠。 在大鼠中通过盲肠结扎诱导脓毒症， 穿刺（CLP）;对照是假手术。 蛋白质合成速率为 在空肠和回肠粘膜和浆膜中使用泛液法在体内测量 14 C-亮氨酸的剂量。 在其他实验中，蛋白质周转率是 在来自对照和脓毒症大鼠的分离的肠细胞中测定。 因为 肠道蛋白质周转的变化可能反映了细胞蛋白质的改变 代谢和/或改变的细胞增殖速率，细胞增殖是 通过测定DNA中的放射性掺入和 进行放射自显影研究后，管理的3 H- 胸苷（1 μ Ci/g b.w.）。 脓毒症对肠道激素合成的影响 并且通过测量血浆血管活性物质的水平来确定释放 肠肽（VIP）、肽YY（PYY）、分泌和胃泌素 对照和脓毒症大鼠，通过分离的肠细胞合成VIP和PYY， 肠壁VIP和PYY mRNA水平。 TNF、IL-1的作用 和IL-6是通过血浆和组织（肠壁）水平阐明的。 细胞因子，并通过给予细胞因子（100 μ- g/kg bw i. p.，在16小时内重复三次给药），然后 肠蛋白周转率的测量。 细胞因子的作用 在诱导脓毒症前2小时给予抗血清， 还将测试合成速率。 最后，谷氨酰胺对 通过孵育分离的肠细胞来测试蛋白质合成 不同浓度（高达3.4 μ M）的氨基酸。 效果 与乙酰乙酸和3-羟基丁酸相比， 检验谷氨酰胺对肠上皮细胞蛋白质的任何影响 合成是由能量供应引起的。 拟议的研究是 重要的是因为脓毒症期间肠道蛋白质代谢的变化 可能极大地影响全身蛋白质经济，也可能与 败血症和危重病期间其他肠道功能的变化。

Protein synthesis is an important function of the intestine, both from a quantitative and qualitative standpoint. The aim of this project is to determine the effect of sepsis on intestinal protein metabolism, synthesis and release of gut peptides, and enterocyte proliferation and migration rates. We will also test the hypothesis that TNF, IL-1 and IL-6 regulate intestinal protein metabolism during sepsis. Finally, we will study the effect of glutamine on protein synthesis in isolated enterocytes from control and septic rats. Sepsis is induced in rats by cecal ligation and puncture (CLP); controls are sham-operated. Protein synthesis rate is measured in vivo in jejunal and ileal mucosa and serosa using a flooding dose of 14C-leucine. In other experiments, protein turnover rates are determined in isolated enterocytes from control and septic rats. Because changes in intestinal protein turnover may reflect altered cellular protein metabolism and or altered cell proliferation rates, cell proliferation is studied by determining incorporation of radioactivity into DNA and by performing autoradiographic studies following the administration of 3H- thymidine (1 mu-Ci/g b.w.). The effect of sepsis on gut hormone synthesis and release is determined by measuring plasma levels of vasoactive intestinal peptide (VIP), peptide YY (PYY), secretion and gastrin in control and septic rats, synthesis of VIP and PYY by isolated enterocytes, and mRNA levels for VIP and PYY in intestinal wall. The role of TNF, IL-1 and IL-6 is elucidated by plasma and tissue (intestinal wall) levels of the cytokines in the septic model and by administering the cytokines (100 mu- g/kg bw i.p. in three repeated does over 16 h) to normal rats followed by measurement of intestinal protein turnover rates. The effect of cytokine antisera administered 2 h before induction of sepsis on intestinal protein synthesis rate will also be tested. Finally, the effect of glutamine on protein synthesis is tested by incubating isolated enterocytes with different concentrations (up to 3.4 micro M) of the amino acid. The effect of glutamine is compared to that of acetoacetate and 3-hydroxybutyrate to test the hypothesis that any effect of glutamine on enterocyte protein synthesis is caused by energy provision. The proposed studies are important because changes in intestinal protein metabolism during sepsis may greatly influence total body protein economy and may also be related to changes in other intestinal functions during sepsis and critical illness.