| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
|
|
|
|||||||
|
|||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
-adrenergic vascular responsiveness to sympathetic nerve activity is intact after head-down bed rest in humans
1 Department of Cardiovascular Dynamics, National Cardiovascular Center Research Institute, Suita, Osaka, Japan; Department of Autonomic Neuroscience, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Aichi, Japan
2 Department of Autonomic Neuroscience, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Aichi, Japan
3 Department of Internal Medicine and Pathophysiology, Nagoya City University Graduate School of Medical Science, Nagoya, Aichi, Japan
4 Department of Cardiovascular Dynamics, National Cardiovascular Center Research Institute, Suita, Osaka, Japan
* To whom correspondence should be addressed. E-mail: kamiya{at}ri.ncvc.go.jp.
Spaceflight and its ground-based simulation model, 6° head-down bed rest (HDBR), cause cardiovascular deconditioning in humans. Since sympathetic vasoconstriction plays a very important role in circulation, we examined whether HDBR impairs 
-adrenergic vascular responsiveness to sympathetic nerve activity. We subjected 8 healthy volunteers to 14 days of HDBR, and before and after HDBR measured calf muscle sympathetic nerve activity (MSNA, microneurography) and calf blood flow (venous occlusion plethysmography) during sympatho-excitatory stimulation (rhythmic handgrip exercise). HDBR did not change the increase in total MSNA (P=0.97) or the decrease in calf vascular conductance (P=0.32) during exercise, but it did augment the increase in calf vascular resistance (P=0.0011). HDBR augmented the transduction gain from total MSNA into calf vascular resistance, assessed as the least-squares linear regression slope of vascular resistance on total MSNA (0.05 ±0.02 before HDBR, 0.20 ±0.06 after HDBR, P=0.0075), but did not change the transduction gain into calf vascular conductance (P=0.41). Our data indicate that -adrenergic vascular responsiveness to sympathetic nerve activity is preserved in the supine position after HDBR in humans.
This article has been cited by other articles:
|
|
 |
|
  H. Edgell, K. A. Zuj, D. K. Greaves, J. K. Shoemaker, M.-A. Custaud, P. Kerbeci, P. Arbeille, and R. L. Hughson WISE-2005: adrenergic responses of women following 56-days, 6{degrees} head-down bed rest with or without exercise countermeasures Am J Physiol Regulatory Integrative Comp Physiol, December 1, 2007; 293(6): R2343 - R2352. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Kamiya, D. Michikami, T. Shiozawa, S. Iwase, J. Hayano, T. Kawada, K. Sunagawa, and T. Mano Bed rest attenuates sympathetic and pressor responses to isometric exercise in antigravity leg muscles in humans Am J Physiol Regulatory Integrative Comp Physiol, May 1, 2004; 286(5): R844 - R850. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
| Visit Other APS Journals Online |
