Hinghofer-Szalkay HG,
Noskov VB, Rössler A, Grigoriev AI, Kvetnansky R, Polyakow VV

Endocrine status and LBNP-induced hormone changes during a 438-day space flight: A case study

Aviat Space Environ Med 1999; 70:1-5

Background: We investigated basal levels and lower body suction (LBNP)-induced changes of volume regulating (PRA, aldosterone, AVP, ANP99-126) and other stress-sensitive hormones (catecholamines, cortisol, ACTH) in venous plasma from one cosmonaut before (-45 days), during (3, 170, 287, 430 days) and after (+4, +90 days) a record-breaking long term (438 d) space flight.

Method: Blood was taken at the beginning and immediately after ending LBNP (-15/-30/-35 mmHg for 15/15/10 minutes) preflight supine, inflight, and postflight supine.

Results: PRA, aldosterone, and vasopressin levels stayed within normal boundaries during the entire flight and after landing. Catecholamines exceeded reference limits (epinephrine >140 pg/ml, NE >1000 pg/ml) 5 and 9 months inflight, and 4 days postflight. ANP and cGMP were lower inflight (p<0.04) than pre- or postflight. Cortisol and ACTH were not consistently altered. LBNP-induced hormonal changes were not different (p>0.05) in µ-G and 1-G.

Conclusion: Based on data from one cosmonaut, we conclude that long-term spaceflight up to 430 days duration appeared to lower plasma ANP and cGMP during flight and occasionally elevate catecholamine levels, without significantly altering LBNP-induced relative hormone changes as compared to those observed on the ground.

Practical considerations: From this case study it can be derived that long-term flight may not pose serious changes within steady-state variables and stimulus-response dynamics of fluid-electrolyte endocrine control. Based on evidence from one cosmonaut, human travel to Mars may be unimpeded in terms of hormonal volume regulation.