Horber F F, Krayer S, Rehder K, Haymond M W
Department of Medicine, Mayo Clinic and Foundation, Rochester, Minnesota 55905.
Anesthesiology. 1988 Sep;69(3):319-26. doi: 10.1097/00000542-198809000-00006.
General anesthesia in combination with surgery is known to result in negative nitrogen balance. To determine whether general anesthesia without concomitant surgery decreases whole body protein synthesis and/or increases whole body protein breakdown, two groups of dogs were studied: Group 1 (n = 6) in the conscious state and Group 2 (n = 8) during general anesthesia employing halothane (1.5 MAC) in 50% nitrous oxide and oxygen. Changes in protein metabolism were estimated by isotope dilution techniques employing simultaneous infusions of [4,53H]leucine and alpha-[1-14C]-ketoisocaproate (KIC). Total leucine carbon flux was unchanged or slightly increased in the anesthetized animals when compared to the conscious controls, indicating only a slight increase in the rate of proteolysis. However, leucine oxidation was increased (P less than 0.001) by more than 80% in the anesthetized animals when compared with their conscious controls, whereas whole body nonoxidative leucine disappearance, an indicator of whole body protein synthesis, was decreased. The ratio of leucine oxidation to the nonoxidative rate of leucine disappearance, which provides an index of the catabolism of at least one essential amino acid in the postabsorptive state, was more than twofold increased (P less than 0.001) in the anesthetized animals regardless of the tracer employed. These studies suggest that the administration of anesthesia alone, without concomitant surgery, is associated with a decreased rate of whole body protein synthesis and increased leucine oxidation, resulting in increased leucine and protein catabolism, which may be underlying or initiating some of the protein wasting known to occur in patients undergoing surgery.
已知全身麻醉联合手术会导致负氮平衡。为了确定无伴随手术的全身麻醉是否会降低全身蛋白质合成和/或增加全身蛋白质分解，对两组犬进行了研究：第1组（n = 6）处于清醒状态，第2组（n = 8）在使用氟烷（1.5 MAC）、50%氧化亚氮和氧气的全身麻醉期间。采用同时输注[4,5-³H]亮氨酸和α-[1-¹⁴C]-酮异己酸（KIC）的同位素稀释技术评估蛋白质代谢的变化。与清醒对照组相比，麻醉动物的总亮氨酸碳通量未改变或略有增加，表明蛋白水解速率仅略有增加。然而，与清醒对照组相比，麻醉动物的亮氨酸氧化增加（P < 0.001）超过80%，而作为全身蛋白质合成指标的全身非氧化亮氨酸消失减少。无论采用何种示踪剂，麻醉动物中亮氨酸氧化与亮氨酸非氧化消失率的比值增加了两倍多（P < 0.001），该比值可作为吸收后状态下至少一种必需氨基酸分解代谢的指标。这些研究表明，单独给予麻醉而无伴随手术，与全身蛋白质合成速率降低和亮氨酸氧化增加有关，导致亮氨酸和蛋白质分解代谢增加，这可能是手术患者已知发生的一些蛋白质消耗的潜在原因或起始因素。
