Clinical Autonomic Research

, 16:121

Neuroendocrine and behavioural responses to CO2 inhalation in central versus peripheral autonomic failure

  • Joey M. Kaye
  • Tim M. Young
  • Christopher J. Mathias
  • Laura Watson
  • Stafford L. Lightman
RESEARCH ARTICLE

DOI: 10.1007/s10286-006-0331-x

Cite this article as:
Kaye, J.M., Young, T.M., Mathias, C.J. et al. Clin Auton Res (2006) 16: 121. doi:10.1007/s10286-006-0331-x

Abstract

Multiple system atrophy (MSA) and pure autonomic failure (PAF) represent distinct pathological models of autonomic failure in humans. We have investigated the neuroendocrine, behavioural and autonomic cardiovascular responses to the 35% CO2 challenge. Nine patients with MSA, nine with PAF and five control subjects received a single breath of 35% CO2. Peripheral autonomic failure (i.e., PAF) was associated with significantly lower resting noradrenaline levels. All groups demonstrated a significant pressor response to CO2. In controls, the mean pressor response was +60.2 mm Hg, which was significantly smaller in both the PAF (+26.8 mm Hg, P < 0.01) and MSA (+18.3 mm Hg, P < 0.001) patients. In addition, the onset of the response was significantly delayed in both MSA (140.2 s) and PAF (154.2 s) patients compared with controls (32.4 s, P = 0.04 and P = 0.03, respectively). Noradrenaline levels increased only in controls. Central autonomic impairment (i.e., MSA) was associated with lower cortisol release (+8.8% in MSA compared with +35.2% in control and +23.7% in PAF) and fewer somatic symptoms of emotional arousal. Both MSA and PAF exhibit marked sympathetic autonomic impairment, however, residual (albeit differing) sympathetic pathways can still maintain a partial cardiovascular response. A central autonomic lesion, however, also appears to be associated with blunting of both cortisol and emotional responses to this stress paradigm.

Key words

multiple system atrophy pure autonomic failure stress autonomic nervous system carbon dioxide 

Copyright information

© Steinkopff-Verlag 2006

Authors and Affiliations

  • Joey M. Kaye
    • 1
    • 3
  • Tim M. Young
    • 2
  • Christopher J. Mathias
    • 2
  • Laura Watson
    • 2
  • Stafford L. Lightman
    • 1
  1. 1.Henry Wellcome Laboratories for Integrative Neuroscience and EndocrinologyUniversity of BristolBristolUK
  2. 2.Autonomic UnitNational Hospital for Neurology and NeurosurgeryLondonUK
  3. 3.Dept. of Endocrinology and DiabetesSir Charles Gairdner HospitalPerth (WA) 6006Australia

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