Validation of transport measurements in skeletal muscle with N-13 amino acids using a rabbit isolated hindlimb model.
Validation of transport measurements in skeletal muscle with N-13 amino acids using a rabbit isolated hindlimb model.
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使用兔离体后肢模型验证 N-13 氨基酸在骨骼肌中的转运测量。
DOI：
10.1016/0024-3205(89)90585-7
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发表时间：
1989
期刊：
影响因子：
6.1
通讯作者：
Brennan,MF
中科院分区：
文献类型：
--
作者：
Conlon,KC;Bading,JR;DiResta,GR;Corbally,MT;Gelbard,AS;Brennan,MF
我们正在研究C-11和N-13标记氨基酸在荷瘤兔体内的转运，以确定氨基酸转运在癌症肌肉萎缩发病机制中的作用。为了验证一种新的体内测量骨骼肌中这些化合物运输的方法，我们在家兔身上建立了一个分离的后肢模型。肢体灌注采用非循环、恒温、恒压系统和无细胞灌注。在灌注的前75分钟测量血液动力学和代谢参数，发现保持正常和稳定。在兔后肢正常静息血流范围内，血流随灌注压力直接变化。记录L-[酰胺N-13]谷氨酰胺或N-13 L-谷氨酸与Tc-99m人血清白蛋白（HSA）联合向股动脉内注射后大腿内侧的时间-活性曲线（TAC）。区域等离子体流量由Tc-99m数据确定。N-13 TAC始终表现出三个阶段的冲洗，分别为30秒，5分钟和2小时。根据N-13数据，使用毛细管和细胞运输的双屏障、单毛细管模型计算毛细管和细胞运输参数，并假设三个洗脱组分分别来自示踪剂通量、提取到间隙和提取到细胞内空间。这一解释得到了验证，该技术对转运过程的敏感性通过检查N-13 TAC的影响和几个已知影响氨基酸细胞转运的因素（即胰岛素浓度、氨基酸浓度和灌注液的pH值）的计算转运参数得到了证明。离体肢体中N-13 l -谷氨酰胺的时间-活性曲线和转运参数与完整兔后肢非常相似，提示灌注模型研究表明氨基酸在体内转运。这里描述的方法特别适合于研究影响骨骼肌中氨基酸代谢的因素（例如，激素和单因子）对运输的特定影响。
We are studying the transport of C-11 and N-13 labeled amino acids in tumor-bearing rabbits to determine the role of amino acid transport in the pathogenesis of muscle wasting in cancer. To validate a new, in vivo, method for measuring transport in skeletal muscle with these compounds, an isolated hindlimb model was developed in rabbits. The limb was perfused with a non-recirculating, normothermic, constant pressure system and a cell-free perfusate. Hemodynamic and metabolic parameters were measured during the first 75 min. of pergusion and found to remain normal and stable. Flow varied directly with perfusion pressure over the normal range of resting flows in the intact rabbit hindlimb. Time-activity curves (TAC's) were recorded from the medial thigh following bolus co-injection of L-[amide N-13] glutamine or N-13 L-glutamate with Tc-99m human serum albumin (HSA) into the femoral artery. Regional plasma flow was determined from the Tc-99m data. The N-13 TAC's consistently manifested a three-phased washout with half times of approximately 30 sec., 5 min. and 2 hr. Capillary and cellular transport parameters were computed from the N-13 data using a double barrier, single capillary model of capillary and cellular transport and assuming that the three washout components result, respectively, from tracer throughput, extraction into the interstitial space and extraction into the intracellular space. This interpretation was validated and the sensitivity of the technique to transport processes demonstrated by examining the effects on the N-13 TAC's and computed transport parameters of several factors known to influence cellular transport of amino acids, viz., the insulin concentration, amino acid concentration and pH of the perfusate. Time-activity curves and transport parameters for N-13 L-glutamine in the isolated limb were very similar to those observed in the intact rabbit hindlimb, suggesting that studies in the perfused model are indicative of amino acid transport in vivo. The methodology described here is especially well suited for studying the specific effects on transport of factors which influence amino acid metabolism in skeletal muscle (e.g., hormones and monokines).
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