The effects of microgravity and space radiation on cardiovascular health: From low-Earth orbit and beyond

Abstract

The unique conditions of space harbor considerable challenges for astronauts to overcome. Namely, the ionizing content of space radiation and the effects of microgravity have been implicated in the pathogenesis of cardiovascular disease. Post-flight carotid arterial stiffness was demonstrated in astronaut studies while early arteriosclerosis has been linked with microgravity-induced oxidative stress in cellular studies. Similarly, radiation has been shown to disrupt molecular pathways, enhance reactive oxygen species and increase risk of cardiovascular disease in exposed populations. These results may bear even more significance in space owing to the propensity for microgravity and space radiation to yield synergistic and/or additive interactions. Potential countermeasures such as α-tocopherol and captopril target these oxidative pathways and may help to protect against the effects of microgravity and radiation-induced cardiac damage. However, more research needs to be conducted in this area to facilitate a safe passage for humans to the Moon, Mars and beyond.

Keywords: Atherosclerosis; Cardiac remodeling; Microgravity; Oxidative stress; Radiation.

Fig. 1

Cardiovascular markers compared pre- and post-flight as derived from the Hughson et al. study .

Fig. 2

Physiological and aberrant pathways in endothelial-derived NO formation. Key: L-arg (L-arginine), NO (nitric oxide), ONOO– (perioxynitrite), eNOS (endothelial nitric oxide synthase), GC (guanyl cyclase), GTP (guanosine triphosphate), cGMP (cyclic guanosine monophosphate), NADPH oxidase (Nicotinamide adenine dinucleotide phosphate oxidase), GPx (glutathione perioxidase), SOD (superoxide dismutase).

Fig. 3

A visual representation of the various sources of ionizing radiation within the cosmos; galactic cosmic rays, solar particle events and trapped charged particles in Van Allen belts.