[The red blood system in men during long-term head-down bed rest]

Area of Science:

• Physiology
• Hematology
• Space Medicine

Background:

• Head-down bedrest (HDBR) is a model for microgravity effects.
• Understanding red blood cell adaptation is crucial for spaceflight and terrestrial health.

Purpose of the Study:

• To investigate hematological changes in male volunteers during a 120-day HDBR study.
• To compare these changes with those experienced by astronauts during space missions.

Main Methods:

• Analysis of erythrocyte count, hemoglobin, iron turnover, immunoglobulins (IgA, IgG, IgM), metabolism, lipids, phospholipids, and lipid peroxidation (LPO).
• Morphological and biochemical investigations were conducted at various time points during HDBR and post-bedrest.

Main Results:

• Early HDBR (day 7) showed increased erythrocyte count and hemoglobin.
• Later HDBR (days 50-100) revealed altered erythrocyte metabolism, increased serum iron and ferritin, elevated cholesterol, intensified LPO, and inhibited antioxidant activity.
• These findings suggest cell membrane destabilization.

Conclusions:

• HDBR induces significant hematological shifts, including red blood cell membrane destabilization.
• The observed changes are comparable to those seen in astronauts after extended space missions.
• This study provides insights into physiological adaptations relevant to both space exploration and prolonged inactivity.