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Kaye J, Buchanan F, Kendrick A, Johnson P, Lowry C, Bailey J, Nutt D, Lightman S.
“Acute carbon dioxide exposure in healthy adults: evaluation of a novel means of investigating the stress response”.
J Neuroendocrinol. 2004 Mar;16(3):256-64.
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Abstract
Acute hypercapnia was studied to assess its potential as a noninvasive and simple test for evoking neuroendocrine, cardiovascular and psychological responses to stress in man. A single breath of four concentrations of carbon dioxide CO2, 5, 25, 35 and 50, was administered to nine healthy volunteers in a randomized, single-blind fashion. Although no adverse effects occurred, most subjects were unable to take a full inspired vital capacity breath of 50 CO2. In response to the remaining exposures, subjective and somatic symptoms of anxiety increased in a dose-dependent manner. Unlike 5 and 25 CO2, 35 CO2 stimulated significant adrenocorticotropic hormone and noradrenaline release at 2 min and cortisol and prolactin release at 15 min following inhalation. This same dose also provoked a significant bradycardia that was followed by an acute pressor response. No significant habituation of psychological, hypothalamic-pituitary-adrenal HPA or cardiovascular responses following 35 CO2 was seen when this dose was repeated after 1 week. A single breath of 35 CO2 safely and reliably produced sympathetic and HPA axis activation and should prove a useful addition to currently available laboratory tests of the human stress response.
Key Words: carbogen
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