Austgen T R, Chen M K, Moore W, Souba W W
Department of Surgery, University of Florida College of Medicine, Gainesville 32610.
Arch Surg. 1991 Jan;126(1):23-7. doi: 10.1001/archsurg.1991.01410250027003.
The effect of endotoxin on renal glutamine metabolism and ammoniagenesis was investigated in vivo in the rat to gain further insight into the altered glutamine flow that characterizes critical illness. Studies were done 15 hours following a single dose of Escherichia coli lipopolysaccharide (10 mg/kg). Renal blood flow and arterial glutamine concentration were similar in control and study rats, but the kidney switched from an organ of slight glutamine uptake in controls (129 +/- 52 nmol/100 g of body weight per minute) to net release in the endotoxin-treated animals (-273 +/- 170 nmol/100 g of body weight per minute). Simultaneously, the specific activity of renal glutamine synthetase increased by almost 50% (374 +/- 40 nmol/mg of protein per hour in rats given endotoxin vs 253 +/- 12 nmol/mg of protein per hour in controls), while glutaminase was unchanged. Urinary ammonia excretion was reduced by 35% in the endotoxin-treated animals (47 +/- 6 mumol/12 h in endotoxin-treated animals vs 70 +/- 8 mumol/12 h in controls) despite a 10% fall in the arterial bicarbonate value. Endotoxin alters the net flux of glutamine across the kidney which appears to be partially regulated enzymatically. This may impair the kidneys' ability to maintain acid/base homeostasis.
为了进一步深入了解在危重病中出现的谷氨酰胺流量改变的情况，我们在大鼠体内研究了内毒素对肾脏谷氨酰胺代谢和氨生成的影响。在给予单剂量大肠杆菌脂多糖（10毫克/千克）15小时后进行研究。对照大鼠和研究大鼠的肾血流量和动脉谷氨酰胺浓度相似，但在对照组中，肾脏是一个轻微摄取谷氨酰胺的器官（每分钟129±52纳摩尔/100克体重），而在内毒素处理的动物中则转变为净释放（每分钟-273±170纳摩尔/100克体重）。同时，肾脏谷氨酰胺合成酶的比活性增加了近50%（给予内毒素的大鼠中为每小时374±40纳摩尔/毫克蛋白质，而对照组中为每小时253±12纳摩尔/毫克蛋白质），而谷氨酰胺酶则没有变化。尽管动脉碳酸氢盐值下降了10%，但内毒素处理的动物的尿氨排泄减少了35%（内毒素处理的动物中为每12小时47±6微摩尔，而对照组中为每12小时70±8微摩尔）。内毒素改变了谷氨酰胺在肾脏中的净通量，这似乎部分受到酶的调节。这可能会损害肾脏维持酸碱平衡的能力。
