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Horm Metab Res 2002; 34(3): 155-159
DOI: 10.1055/s-2002-23200
Original Clinical
© Georg Thieme Verlag Stuttgart · New York

Effect of Simulated Microgravity on Endocrine Response to Insulin-Induced Hypoglycemia in Physically Fit Men

L.  Ksinantova 1 , J.  Koska 1 , R.  Kvetnansky 1 , M.  Marko 2 , D.  Hamar 3 , M.  Vigas 1
  • 1Institute of Experimental Endocrinology Slovak Academy of Sciences
  • 2Hospital of Ministry of Defence, Slovak Republic
  • 3Faculty of Physical Education and Sports, Comenius University, Bratislava, Slovak Republic
Further Information

Publication History

10 July 2001

31 October 2001

Publication Date:
26 March 2002 (online)

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Abstract

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° 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.

Key words

Bed Rest - Catecholamines - Adenopituitary Hormones - PRA

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Lucia Ksinantova, M.D.

Institute of Experimental Endocrinology · Slovak Academy of Sciences

Vlarska 3 · 833 06 Bratislava · Slovak Republic

Phone: + 421 (2) 5477 4942

Fax: + 421 (2) 5477 4247 ·

Email: ueenksin@savba.sk