Korean J Anesthesiol.  2008 Nov;55(5):602-606. 10.4097/kjae.2008.55.5.602.

Impaired but reversible vascular reactivity in a rat model of microgravity

• Kim SY
• Lim HK
• Lee YB
• Choi JC
• Park JT
• Ahn MC
• Lee KH

• KMID: 2243002
• DOI: http://doi.org/10.4097/kjae.2008.55.5.602

Abstract

BACKGROUND: The hindlimb unweighting (HLU) rat model mimics cardiovascular deconditioning following microgravity or human bed rest, particularly for the development of orthostatic intolerance. We have examined vascular responses to alpha1 adrenergic and non-alpha1 adrenergic agonists in vitro. We have also explored the reversibility of the contractile abnormalities observed.
METHODS
Dose-response curves were generated to phenylephrine (PE) and norepinephrine (NE) (10(-9) to 10(-4) M), U46619 (U4) (10(-10) to 10(-6) M) at one-half log order intervals in controls (n = 6), HLU (n = 6), or recovered rats (n = 6). EC(50)s and maximal responses (E(max)) were calculated by nonlinear logistic regression analysis with PRIZM software (Graphpad, Mountain View, CA).
RESULTS
Simulated microgravity results in attenuated contractile responses to both alpha1 adrenergic and non-alpha1 adrenergic agonists, but the impaired contractile phenomenon reverses with time.
CONCLUSIONS
The decreased vascular reactivity after microgravity and prolonged bed rest could cause attenuated baroreflex function and produce orthostatic intolerance, but that problem resolved with time.

Keyword

hindlimb unweighting; microgravity; orthostatic intolerance

MeSH Terms

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid
Adrenergic Agonists
Animals
Baroreflex
Bed Rest
Cardiovascular Deconditioning
Hindlimb
Humans
Logistic Models
Norepinephrine
Orthostatic Intolerance
Phenylephrine
Rats
Weightlessness
15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid
Adrenergic Agonists
Norepinephrine
Phenylephrine