Garber A J, Karl I E, Kipnis D M
J Biol Chem. 1976 Feb 10;251(3):851-7.
Alanine and glutamine formation and release were studied using the intact epitrochlaris preparation of rat skeletal muscle. Epinephrine reduced the release of alanine and glutamine in a concentration-dependent manner. Measurable inhibition was observed at 10(-9) M epinephrine, and maximal inhibition was obtained at 10(-5) M. Norepinephrine also reduced alanine and glutamine formation and release but the concentration required for maximal inhibition was approximately 100-fold greater than for epinephrine. Isoproterenol (beta agonist), but not phenylephrine (alpha agonist), reproduced the effects of epinephrine, and propranolol (beta antagonist), but not phentolamine (alpha antagonist), blocked the effect of the catecholamine. N6,O2'-Dibutyryl adenosine 3':5'-monophosphate reproduced the effects of epinephrine and theophylline potentiated the effect of submaximal concentrations of the hormone. Glucagon and prostaglandin E2 had no observable effect on amino acid release. Insulin did not modify the inhibition of alanine and glutamine release produced by epinephrine. Alanine and glutamine formation from added precursor amino acids was unaffected by epinephrine or cyclic adenosine 3':5'-monophosphate. Epinephrine reduced alanine formation in muscles obtained from diabetic rats or animals treated with thyroxine or cortisone. These findings indicate that physiological levels of catecholamines reduce alanine and glutamine formation and release from skeletal muscle. This effect is mediated by a beta-adrenergic receptor and the adenylate cyclase system and can be accounted for by an inhibition of muscle protein degradation.
利用大鼠骨骼肌完整的肱三头肌制备物研究了丙氨酸和谷氨酰胺的生成及释放。肾上腺素以浓度依赖的方式降低丙氨酸和谷氨酰胺的释放。在10^(-9) M肾上腺素时观察到可测量的抑制作用，在10^(-5) M时获得最大抑制作用。去甲肾上腺素也降低丙氨酸和谷氨酰胺的生成及释放，但最大抑制所需的浓度比肾上腺素大约高100倍。异丙肾上腺素（β激动剂）而非去氧肾上腺素（α激动剂）重现了肾上腺素的作用，普萘洛尔（β拮抗剂）而非酚妥拉明（α拮抗剂）阻断了儿茶酚胺的作用。N6,O2'-二丁酰腺苷3':5'-单磷酸重现了肾上腺素的作用，茶碱增强了亚最大浓度激素的作用。胰高血糖素和前列腺素E2对氨基酸释放没有可观察到的影响。胰岛素没有改变肾上腺素所致的丙氨酸和谷氨酰胺释放的抑制作用。从添加的前体氨基酸生成丙氨酸和谷氨酰胺不受肾上腺素或环腺苷3':5'-单磷酸的影响。肾上腺素降低了从糖尿病大鼠或用甲状腺素或可的松处理的动物获得的肌肉中丙氨酸的生成。这些发现表明，儿茶酚胺的生理水平降低了骨骼肌中丙氨酸和谷氨酰胺的生成及释放。这种作用由β-肾上腺素能受体和腺苷酸环化酶系统介导，并且可以通过抑制肌肉蛋白质降解来解释。
