Ksinantova L, Koska J, Kvetnansky R, Marko M, Hamar D, Vigas M
Institute of Experimental Endocrinology, Slovak Academy of Sciences, Bratislava, Slovak Republic.
Horm Metab Res. 2002 Mar;34(3):155-9. doi: 10.1055/s-2002-23200.
Adaptation to microgravity is associated with alteration in some endocrine functions. In the present longitudinal study, the counterregulatory hormonal response to insulin-induced hypoglycemia (ITT, 0.1 IU/kg short acting insulin i. v.) was evaluated under simulated microgravity conditions in 15 physically fit subjects. ITT was performed at the beginning of the investigation, and again after completion of 6 weeks of endurance training and after a subsequent period of 4 days of head-down bed rest at a backward tilt of 6 degrees from the horizontal. Endurance training showed a significant increase in maximal aerobic capacity in previously well-trained subjects (increase by 12 %), as well as on attenuation of counterregulatory response of epinephrine to hypoglycemia. After 4 days of bed rest, basal concentrations of plasma norepinephrine was diminished (p < 0.002) and plasma renin activity was enhanced (p < 0.02). After bed rest, decreased responses of the two catecholamines (norepinephrine, p < 0.001; epinephrine, p < 0.001), growth hormone (p < 0.001), and cortisol (p < 0.05) were observed. Response of plasma renin activity after bed rest was increased (p < 0.01). This longitudinal study indicated that 4 days of bed rest in endurance-trained subjects induced increased response of PRA to hypoglycemia and attenuation of other counterregulatory neuroendocrine responses.
对微重力的适应与某些内分泌功能的改变有关。在本纵向研究中，对15名身体健康的受试者在模拟微重力条件下评估了对胰岛素诱导的低血糖（胰岛素耐量试验，静脉注射0.1 IU/kg短效胰岛素）的反调节激素反应。胰岛素耐量试验在研究开始时进行，在6周耐力训练结束后以及随后从水平向后倾斜6度的头低位卧床休息4天后再次进行。耐力训练显示，在先前训练有素的受试者中，最大有氧能力显著增加（增加12%），同时肾上腺素对低血糖的反调节反应减弱。卧床休息4天后，血浆去甲肾上腺素的基础浓度降低（p<0.002），血浆肾素活性增强（p<0.02）。卧床休息后，观察到两种儿茶酚胺（去甲肾上腺素，p<0.001；肾上腺素，p<0.001）、生长激素（p<0.001）和皮质醇（p<0.05）的反应降低。卧床休息后血浆肾素活性的反应增加（p<0.01）。这项纵向研究表明，耐力训练的受试者卧床休息4天会导致肾素活性对低血糖的反应增加以及其他反调节神经内分泌反应减弱。
