Karlstad M D, Sayeed M M
Am J Physiol. 1985 Feb;248(2 Pt 2):R142-6. doi: 10.1152/ajpregu.1985.248.2.R142.
We studied alpha-aminoisobutyric acid (AIB) transport by skeletal muscle and the effect of insulin and Na+ on the transport process during endotoxic shock. Rats (140-160 g) were injected with Salmonella enteritidis endotoxin (20 mg/kg iv) or saline and killed 5 h later. At that time an elevation of blood lactate and hypoglycemia marked the onset of shock in rats given endotoxin. AIB uptake was measured in isolated soleus muscles in vitro. Total cellular AIB uptake in the endotoxic muscles was 25, 28, and 47% lower than control muscles at 1-, 2-, or 3-h incubations, respectively. Insulin stimulated AIB uptake to a lesser extent in endotoxic muscles (from a basal value of 11.62 +/- 0.29 nmol X g dry wt-1 X 3 h-1 to 15.88 +/- 0.64, 19.10 +/- 1.06, and 18.78 +/- 0.52 at 1, 10, and 100 mU/ml insulin, respectively) than in controls (from 17.07 +/- 0.51 to 27.13 +/- 1.16, 27.25 +/- 0.93, and 29.01 +/- 1.09). Na+-dependent AIB uptake, calculated as the difference between AIB uptake in the presence and absence of Na+, was decreased in the endotoxic muscles to 36% of the control value. Na+-independent AIB uptake (measured in Na+-free media) was the same in control and endotoxic muscles. These results suggest that the decrease in both basal and insulin-stimulated AIB transport was due to the decrease in Na+-dependent AIB transport by skeletal muscle during endotoxic shock.
我们研究了骨骼肌对α-氨基异丁酸（AIB）的转运以及内毒素休克期间胰岛素和钠离子对该转运过程的影响。将体重140 - 160克的大鼠静脉注射肠炎沙门氏菌内毒素（20毫克/千克）或生理盐水，5小时后处死。此时，注射内毒素的大鼠血液乳酸升高和低血糖标志着休克的开始。体外测量分离的比目鱼肌对AIB的摄取。内毒素处理的肌肉在1小时、2小时或3小时孵育时，细胞对AIB的总摄取量分别比对照肌肉低25%、28%和47%。胰岛素对内毒素处理的肌肉中AIB摄取的刺激程度较小（基础值为11.62±0.29纳摩尔×克干重⁻¹×3小时⁻¹，在胰岛素浓度为1、10和100毫单位/毫升时分别升至15.88±0.64、19.10±1.06和18.78±0.52），而在对照肌肉中（从17.07±0.51升至27.13±1.16、27.25±0.93和29.01±1.09）。以内毒素处理的肌肉中，钠离子依赖性AIB摄取量（计算为存在和不存在钠离子时AIB摄取量的差值）降至对照值的36%。钠离子非依赖性AIB摄取量（在无钠培养基中测量）在对照和内毒素处理的肌肉中相同。这些结果表明，内毒素休克期间基础和胰岛素刺激的AIB转运减少是由于骨骼肌中钠离子依赖性AIB转运减少所致。
