Proposed role of the paraventricular nucleus in cardiovascular deconditioning

Patrick J. Mueller, J. T. Cunningham, K. P. Patel, E. M. Hasser

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

Aim: Cardiovascular deconditioning occurs in individuals exposed to prolonged spaceflight or bedrest and is associated with the development of orthostatic intolerance. Although the precise mechanisms remain to be fully elucidated, astronauts returning from space or bedrest patients returning to normal upright posture present with decreases in plasma volume and alterations in autonomic function. The hindlimb unloaded (HU) rat has been a useful model to study the effects of cardiovascular deconditioning as it mimics many of the changes that occur after spaceflight and bedrest. Results: Experiments performed in HU rats suggest that cardiovascular deconditioning attenuates baroreflex mediated sympathoexcitation and enhances cardiopulmonary receptor mediated sympathoinhibition. These alterations appear to be due to changes in the central nervous system and may contribute to the pre disposition towards orthostatic intolerance associated with cardiovascular deconditioning. The paraventricular nucleus (PVN) of the hypothalamus is important in basal and reflex control of sympathetic outflow. Recent evidence suggests that nitric oxide (NO) is an important inhibitory neurotransmitter in the PVN and that alterations in nitroxidergic transmission in the PVN may be involved in elevated sympathetic tone in certain disease states. Conclusion: Based on evidence from other laboratories and published and preliminary data from our own laboratories, this review proposes a role for the PVN in cardiovascular deconditioning. In particular, we discuss the hypothesis that increased NO in the PVN contributes to the altered cardiovascular reflexes observed following deconditioning and how these reflexes may be related to the orthostatic intolerance observed after prolonged spaceflight or bedrest.

Original languageEnglish (US)
Pages (from-to)27-35
Number of pages9
JournalActa Physiologica Scandinavica
Volume177
Issue number1
DOIs
StatePublished - Jan 18 2003

Fingerprint

Cardiovascular Deconditioning
Paraventricular Hypothalamic Nucleus
Bed Rest
Orthostatic Intolerance
Space Flight
Reflex
Hindlimb
Nitric Oxide
Astronauts
Baroreflex
Plasma Volume
Posture
Hypothalamus
Neurotransmitter Agents
Central Nervous System

Keywords

  • Arterial baroreflex
  • Cardiopulmonary reflex
  • Hindlimb suspension
  • Orthostatic intolerance
  • Sympathetic nerve activity

ASJC Scopus subject areas

  • Physiology

Cite this

Proposed role of the paraventricular nucleus in cardiovascular deconditioning. / Mueller, Patrick J.; Cunningham, J. T.; Patel, K. P.; Hasser, E. M.

In: Acta Physiologica Scandinavica, Vol. 177, No. 1, 18.01.2003, p. 27-35.

Research output: Contribution to journalArticle

Mueller, Patrick J. ; Cunningham, J. T. ; Patel, K. P. ; Hasser, E. M. / Proposed role of the paraventricular nucleus in cardiovascular deconditioning. In: Acta Physiologica Scandinavica. 2003 ; Vol. 177, No. 1. pp. 27-35.
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