Cardiovascular reactivity to mental stress is not affected by alpha2-adrenoreceptor activation or inhibition.
BACKGROUND
It has been postulated that cardiovascular reactivity to mental stress varies with tonic central sympathetic nervous system activity, but pharmacological evidence is missing.


OBJECTIVE
To test whether modulation of central sympathetic nervous system activity by alpha2-adrenergic agonism and antagonism affects cardiovascular reactivity to mental stress.


METHODS
On three five-stepped dose/concentration-response study days, 12 healthy male volunteers received intravenous infusions of dexmedetomidine (alpha2-agonist, target plasma concentrations: 0.04-0.32 ng/ml), yohimbine (alpha2-antagonist, doses: 0.016-0.125 mg/kg), and placebo, respectively. During each dose step, subjects performed a 5-Choice Reaction Time Task (CRTT) and a Paced Auditory Serial Addition Task (PASAT) to induce moderate mental stress. Prestress baseline, as well as stress-induced responses of heart rate, and noninvasive finger arterial blood pressure (Finapres) were assessed.


RESULTS
Prestress baseline heart rate and blood pressure decreased with increasing doses of dexmedetomidine and increased with increasing doses of yohimbine. However, dexmedetomidine and yohimbine did not affect stress-induced heart-rate and blood-pressure changes.


CONCLUSIONS
Cardiovascular reactivity to mental stress is not related to pharmacologically manipulated tonic central sympathetic nervous system activity by alpha2-adrenergic agonists and antagonists. These results do not support the assumption that cardiovascular reactivity is an index of tonic central sympathetic nervous system activity.
Philippsen
Christine
C
Division of Clinical Physiology, Graduate School of Psychobiology, University of Trier, Johanniterufer 15, 54290, Trier, Germany.
Hahn
Melanie
M
Schwabe
Lars
L
Richter
Steffen
S
Drewe
Jürgen
J
Schachinger
Hartmut
H
D058647:Adrenergic alpha-2 Receptor Agonists; D058669:Adrenergic alpha-2 Receptor Antagonists; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000328:Adult; D001143:Arousal / Q000187:drug effects / Q000502:physiology*; D001288:Attention / Q000187:drug effects / Q000502:physiology; D001341:Autonomic Nervous System / Q000187:drug effects / Q000502:physiology; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology*; D002755:Choice Behavior / Q000187:drug effects / Q000502:physiology*; D003118:Color Perception / Q000187:drug effects / Q000502:physiology; D020927:Dexmedetomidine / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D011340:Problem Solving / Q000187:drug effects / Q000502:physiology*; D011597:Psychomotor Performance / Q000187:drug effects / Q000502:physiology; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology*; D018341:Receptors, Adrenergic, alpha-2 / Q000502:physiology; D012691:Serial Learning / Q000187:drug effects / Q000502:physiology; D013315:Stress, Psychological / Q000150:complications* / Q000503:physiopathology; D015016:Yohimbine / Q000494:pharmacology*
D058647:Adrenergic alpha-2 Receptor Agonists; D058669:Adrenergic alpha-2 Receptor Antagonists; D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D018341:Receptors, Adrenergic, alpha-2; D015016:Yohimbine; D020927:Dexmedetomidine