Nieto J L, Laviada I D, Guillén A, Haro A
Departamento de Bioquímica y Biología Molecular I. Fac. Químicas. UCM.Ciudad Universitaria, Spain.
Biochem Pharmacol. 1996 May 17;51(10):1321-9. doi: 10.1016/0006-2952(96)00040-8.
Adaptive changes in the beta-adrenergic adenylyl cyclase (AC) system in response to endurance training were studied in heart and adipose tissue. Training was performed by making male Wistar rats run on a motor-driven treadmill. The changes following exercise training were opposite in the two tissue studied. The density of beta-adrenergic receptors in left ventricular membranes of trained rats showed a marked decrease. Comparison of AC activities in cardiac membranes prepared from trained and sedentary rats revealed a depressing effect of endurance training on: 1. the beta-adrenergic stimulatory pathway and the inhibition of AC via receptor; 2. the Gs component and the Gs-adenylyl cyclase coupling, as shown by the response of adenylyl cyclase to GppNHp and NaF; and 3. the enzyme catalytic activity in the presence of Mn2+ or forskolin. The levels of Gsalpha subunits in the left ventricle, as measured in terms of ADP-ribosylated and immunologically reactive proteins, were decreased by endurance exercise, whereas immunodetectable levels of Gialpha2 increased in the membranes of trained myocardium. In contrast to the diminished sensitivity that characterizes the behavior of the cardiac beta-adrenergic-AC system, endurance physical training increased sensitivity of this signal transduction system in adipose tissue. Thus, the density of beta-ARs as well as AC activity and the beta-adrenergic stimulatory pathway were increased in adipose membranes of trained rats compared with the corresponding sedentary controls. In addition, the levels of Gsalpha subunits were higher in the adipose plasma membranes of trained rats. However, immunodetectable levels of Gi1alpha and Gi3alpha increased with training, whereas the amount of Gi2alpha decreased in membranes of trained rats. In conclusion, the present study shows that chronic exercise is associated with a tissue-specific adaptation of the beta-adrenergic AC system.
研究了心脏和脂肪组织中β-肾上腺素能腺苷酸环化酶（AC）系统对耐力训练的适应性变化。通过让雄性Wistar大鼠在电动跑步机上跑步进行训练。在研究的两种组织中，运动训练后的变化相反。训练大鼠左心室膜中β-肾上腺素能受体的密度显著降低。比较训练大鼠和久坐大鼠制备的心脏膜中的AC活性，发现耐力训练对以下方面有抑制作用：1. β-肾上腺素能刺激途径和通过受体对AC的抑制；2. Gs成分和Gs-腺苷酸环化酶偶联，如腺苷酸环化酶对GppNHp和NaF的反应所示；3. 在存在Mn2+或福斯高林的情况下酶的催化活性。以ADP-核糖基化和免疫反应性蛋白衡量，耐力运动使左心室中Gsα亚基的水平降低，而训练心肌膜中可免疫检测到的Giα2水平升高。与心脏β-肾上腺素能-AC系统行为特征的敏感性降低相反，耐力体育训练增加了脂肪组织中该信号转导系统的敏感性。因此，与相应的久坐对照相比，训练大鼠脂肪膜中β-ARs的密度以及AC活性和β-肾上腺素能刺激途径均增加。此外，训练大鼠脂肪质膜中Gsα亚基的水平更高。然而，可免疫检测到的Gi1α和Gi3α水平随训练增加，而训练大鼠膜中Gi2α的量减少。总之，本研究表明，长期运动与β-肾上腺素能AC系统的组织特异性适应有关。
