The kidney in space

Abstract

Renal adaptation in space has been studied during various space missions since the early 70s. Technical and financial disadvantages of performing experiments under real microgravity conditions have warranted the conductance of relative studies under simulated weightlessness on earth. Arriving in microgravity leads to a redistribution of body fluids to the upper part of the body and an exaggerated extravasation very early in-flight. Plasma volume as well as skin evaporation and oral hydration are reduced, while total body water seems to remain stable. Urinary sodium is diminished and a substantial amount of sodium is retained outside the intravascular space. Glomerular filtration rate shows a transient mild increase. Urinary albumin excretion is reduced although initial studies had demonstrated the opposite. Examination of renal histopathology after exposure to simulated microgravity in rats revealed glomerular atrophy, interstitial edema, and degeneration of renal tubular cells. Acute urinary retention which has been reported during spaceflights can lead to certain medical complications that could compromise an entire mission. Kidney stone formation is another important potential hazard for any manned spaceflight. Increased kidney stone formation in space is attributed to several factors including reduced fluid intake, hypercalciuria, and the presence of nanobacteria. Nutritional and pharmacological interventions are currently recommended as preventive measures against renal stone formation in space travelers.

Integrated RNA-seq Analysis Indicates Asynchrony in Clock Genes between Tissues under Spaceflight

“…In addition, during a Mars simulation study in humans, the hormones aldosterone and cortisol fluctuated for longer-than-usual periods despite constant salt intake, suggesting that clock genes may be involved in water–mineral balance [ 47 ]. Few studies have examined the responses of adrenal glands and kidneys in spaceflight [ 45 , 47 , 48 , 49 , 50 , 51 ]. Therefore, our observed asynchrony of clock genes in these three tissues may provide new molecular-level insights about the endocrine systems and water–mineral balance regulation during spaceflight.…”

Gene-metabolite profile integration to understand the cause of spaceflight induced immunodeficiency

“…Supporting evidence came from recent studies that suggested major roles of immunity and energy/lipid metabolism on spaceflight-induced stress. 27 , 70 , 71 We could further expand our knowledge by following up to target the cell lines with in vitro assays linked to immunity, 72 kidney, 73 and liver 71 functions that are important to spaceflight-induced stress. In fact, our forthcoming study will particularly focus on the role of immunity and metabolism in the potential bone loss in vitro during spaceflight.…”

The Impact of Sex and Gender on Adaptation to Space: Executive Summary

“…There is an increased incidence of spaceflight-associated dehydration and hypercalciuria, thereby increasing the risk of calcium oxalate stones in both female and male astronauts. 59 While the overall incidence is not much different from that found on Earth, urinary tract infections in space are more common in women and have been successfully treated with antibiotics. 60 Transient difficulties with urination are reported by both sexes, but the only astronauts requiring catheterization have been women.…”