Orthostatic heart rate responses after prolonged space flights

Tank, Jens; Baevsky, R. M.; Funtova, I.I.; Diedrich, André; Slepchenkova, Irina N.; Jordan, Jens

doi:10.1007/s10286-010-0106-2

Cited by 27 publications

(13 citation statements)

References 12 publications

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“…In a recent study of 18 cosmonauts returning from long-duration flights, only three reported mild orthostatic symptoms during 10 minute standing (61). Neither orthostatic hypotension nor presyncope were observed in any subject.…”

Section: In-flight Countermeasuresmentioning

confidence: 99%

The function of the autonomic nervous system during spaceflight

2015

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Introduction Despite decades of study, a clear understanding of autonomic nervous system activity in space remains elusive. Differential interpretation of fundamental data have driven divergent theories of sympathetic activation and vasorelaxation. Methods This paper will review the available in-flight autonomic and hemodynamic data in an effort to resolve these discrepancies. The NASA NEUROLAB mission, the most comprehensive assessment of autonomic function in microgravity to date, will be highlighted. The mechanisms responsible for altered autonomic activity during spaceflight, which include the effects of hypovolemia, cardiovascular deconditioning, and altered central processing, will be presented. Results The NEUROLAB experiments demonstrated increased sympathetic activity and impairment of vagal baroreflex function during short-duration spaceflight. Subsequent non-invasive studies of autonomic function during spaceflight have largely reinforced these findings, and provide strong evidence that sympathetic activity is increased in space relative to the supine position on Earth. Others have suggested that microgravity induces a state of relative vasorelaxation and increased vagal activity when compared to upright posture on Earth. These ostensibly disparate theories are not mutually exclusive, but rather directly reflect different pre-flight postural controls. Conclusion When these results are taken together, they demonstrate that the effectual autonomic challenge of spaceflight is small, and represents an orthostatic stress less than that of upright posture on Earth. In-flight countermeasures, including aerobic and resistance exercise, as well as short-arm centrifugation have been successfully deployed to counteract these mechanisms. Despite subtle changes in autonomic activity during spaceflight, underlying neurohumoral mechanisms of the autonomic nervous system remain intact and cardiovascular function remains stable during long-duration flight.

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Section: In-flight Countermeasuresmentioning

confidence: 99%

The function of the autonomic nervous system during spaceflight

2015

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“…When gravitational force is modified, as in the case of spaceflight, the physiology of human and animal body can experience various modifications altering the homeostasis balance (Cavolina et al ., ; Davis et al ., ; Zayzafoon et al ., ; Cancedda et al ., ; Tavella et al ., ). Bone disuse and bone loss effects can be considered some of the consequences related to spaceflight experience and they may represent an accelerated model of the osteoporosis disease in normal gravity conditions (Williams et al ., ; Vernikos and Schneider, ; Tavella et al ., ); moreover, space adaptation involves other complex changes in the organism physiology (Suganuma et al ., ; Iwamoto et al ., ; Gridley et al ., ; Tank et al ., ; Masini et al ., ; Rizzo et al ., ; Sandona et al ., ; Smith et al ., ).…”

Section: Introductionmentioning

confidence: 98%

Bone mechanobiology, gravity and tissue engineering: effects and insights

Ruggiu

Cancedda

2014

J Tissue Eng Regen Med

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Bone homeostasis strongly depends on fine tuned mechanosensitive regulation signals from environmental forces into biochemical responses. Similar to the ageing process, during spaceflights an altered mechanotransduction occurs as a result of the effects of bone unloading, eventually leading to loss of functional tissue. Although spaceflights represent the best environment to investigate near-zero gravity effects, there are major limitations for setting up experimental analysis. A more feasible approach to analyse the effects of reduced mechanostimulation on the bone is represented by the 'simulated microgravity' experiments based on: (1) in vitro studies, involving cell cultures studies and the use of bioreactors with tissue engineering approaches; (2) in vivo studies, based on animal models; and (3) direct analysis on human beings, as in the case of the bed rest tests. At present, advanced tissue engineering methods allow investigators to recreate bone microenvironment in vitro for mechanobiology studies. This group and others have generated tissue 'organoids' to mimic in vitro the in vivo bone environment and to study the alteration cells can go through when subjected to unloading. Understanding the molecular mechanisms underlying the bone tissue response to mechanostimuli will help developing new strategies to prevent loss of tissue caused by altered mechanotransduction, as well as identifying new approaches for the treatment of diseases via drug testing. This review focuses on the effects of reduced gravity on bone mechanobiology by providing the up-to-date and state of the art on the available data by drawing a parallel with the suitable tissue engineering systems.

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“…4,11,12 Most patients are able to resume their normal daily activities, although recovery can be quite prolonged, and some patients with more severe symptoms can remain significantly symptomatic. 11 Recently, the role of deconditioning in perpetuating or even causing PoTS has been suggested, 13,14 and the beneficial effects of exercise training in ameliorating symptoms of orthostatic intolerance have been reported. 13,15 There are no other reported cases of PoTS responsive to immunoglobulin therapy nor it is suggested that immunoglobulin or corticosteroid therapy would be suitable for most patients with PoTS.…”

Section: Discussionmentioning

confidence: 99%