Abstract
The haemodynamic and autonomic effects of prolonged exposure to simulated microgravity were assessed non-invasively in seven healthy volunteers completing a 42-day -6° head down tilt. Before, during and after head down tilt, subjects were exposed to moderate excitatory stimuli (mental arithmetic and static handgrip) to gauge possible progressive impairment of pressor responses. Before and after head down tilt, subjects were also exposed to orthostatic stress, to assess influences of simulated microgravity on orthostatic defence. Simple haemodynamics (heart rate and systolic arterial blood pressure), linear (i.e., oscillatory) components of beat-by-beat variability, non-linear properties (i.e., corrected conditional entropy (CCE)) of RR interval variability, and baroreflex slope furnished a non-invasive evaluation of autonomic regulatory mechanisms. Pressor responses to mental arithmetic and to handgrip were markedly impaired after 42 days head down tilt, whereas responses in markers of autonomic regulation were not modified. Standing, performed 8 days after head down tilt to limit the risk of syncope, still induced a variable degree of hypotension, with signs of progressively greater sympathetic activation than before head down tilt. Simulated microgravity-induced reduction of pressor responses, in spite of largely maintained autonomic activation, favours the hypothesis of a peripheral impairment of cardiovascular homeostasis.
| Original language | English |
|---|---|
| Pages (from-to) | 85-95 |
| Number of pages | 11 |
| Journal | Autonomic Neuroscience: Basic and Clinical |
| Volume | 91 |
| Issue number | 1-2 |
| DOIs | |
| Publication status | Published - Aug 13 2001 |
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Keywords
- Autonomic nervous system
- Baroreflex
- Head down bed rest
- Spectral analysis
ASJC Scopus subject areas
- Clinical Neurology
- Cellular and Molecular Neuroscience
- Endocrine and Autonomic Systems
Cite this
Selective impairment of excitatory pressor responses after prolonged simulated microgravity in humans. / Pagani, Massimo; Iellamo, Ferdinando; Lucini, Daniela; Cerchiello, Manfredo; Castrucci, Filippo; Pizzinelli, Paolo; Porta, Alberto; Malliani, Alberto.
In: Autonomic Neuroscience: Basic and Clinical, Vol. 91, No. 1-2, 13.08.2001, p. 85-95.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Selective impairment of excitatory pressor responses after prolonged simulated microgravity in humans
AU - Pagani, Massimo
AU - Iellamo, Ferdinando
AU - Lucini, Daniela
AU - Cerchiello, Manfredo
AU - Castrucci, Filippo
AU - Pizzinelli, Paolo
AU - Porta, Alberto
AU - Malliani, Alberto
PY - 2001/8/13
Y1 - 2001/8/13
N2 - The haemodynamic and autonomic effects of prolonged exposure to simulated microgravity were assessed non-invasively in seven healthy volunteers completing a 42-day -6° head down tilt. Before, during and after head down tilt, subjects were exposed to moderate excitatory stimuli (mental arithmetic and static handgrip) to gauge possible progressive impairment of pressor responses. Before and after head down tilt, subjects were also exposed to orthostatic stress, to assess influences of simulated microgravity on orthostatic defence. Simple haemodynamics (heart rate and systolic arterial blood pressure), linear (i.e., oscillatory) components of beat-by-beat variability, non-linear properties (i.e., corrected conditional entropy (CCE)) of RR interval variability, and baroreflex slope furnished a non-invasive evaluation of autonomic regulatory mechanisms. Pressor responses to mental arithmetic and to handgrip were markedly impaired after 42 days head down tilt, whereas responses in markers of autonomic regulation were not modified. Standing, performed 8 days after head down tilt to limit the risk of syncope, still induced a variable degree of hypotension, with signs of progressively greater sympathetic activation than before head down tilt. Simulated microgravity-induced reduction of pressor responses, in spite of largely maintained autonomic activation, favours the hypothesis of a peripheral impairment of cardiovascular homeostasis.
AB - The haemodynamic and autonomic effects of prolonged exposure to simulated microgravity were assessed non-invasively in seven healthy volunteers completing a 42-day -6° head down tilt. Before, during and after head down tilt, subjects were exposed to moderate excitatory stimuli (mental arithmetic and static handgrip) to gauge possible progressive impairment of pressor responses. Before and after head down tilt, subjects were also exposed to orthostatic stress, to assess influences of simulated microgravity on orthostatic defence. Simple haemodynamics (heart rate and systolic arterial blood pressure), linear (i.e., oscillatory) components of beat-by-beat variability, non-linear properties (i.e., corrected conditional entropy (CCE)) of RR interval variability, and baroreflex slope furnished a non-invasive evaluation of autonomic regulatory mechanisms. Pressor responses to mental arithmetic and to handgrip were markedly impaired after 42 days head down tilt, whereas responses in markers of autonomic regulation were not modified. Standing, performed 8 days after head down tilt to limit the risk of syncope, still induced a variable degree of hypotension, with signs of progressively greater sympathetic activation than before head down tilt. Simulated microgravity-induced reduction of pressor responses, in spite of largely maintained autonomic activation, favours the hypothesis of a peripheral impairment of cardiovascular homeostasis.
KW - Autonomic nervous system
KW - Baroreflex
KW - Head down bed rest
KW - Spectral analysis
UR - http://www.scopus.com/inward/record.url?scp=0035855404&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0035855404&partnerID=8YFLogxK
U2 - 10.1016/S1566-0702(01)00302-2
DO - 10.1016/S1566-0702(01)00302-2
M3 - Article
C2 - 11515805
AN - SCOPUS:0035855404
VL - 91
SP - 85
EP - 95
JO - Autonomic Neuroscience: Basic and Clinical
JF - Autonomic Neuroscience: Basic and Clinical
SN - 1566-0702
IS - 1-2
ER -