Nociception from blood vessels is independent of the sympathetic nervous system under physiological conditions in humans.
To test the hypothesis that vascular pain depends on sympathetic drive under physiological conditions we studied the effects of both alpha-adrenoceptor stimulation by noradrenaline and alpha-adrenoceptor blockade by phentolamine on the intensity of physicochemically evoked pain from veins in humans. In seven healthy volunteers, a vascularly isolated hand vein segment was perfused continuously with noradrenaline (6 x 10(-9)-6 x 10(-6) M), or phentolamine (1.24 x 10(-4) M). Pain was evoked by intraluminal electrostimulation or by injection of hyperosmolar saline during control perfusion of isoosmolar saline and after each noradrenaline concentration, as well as after perfusion of phentolamine. Subjects rated pain intensity continuously on an electronically controlled visual analogue scale (VAS) between 0% VAS (no pain) and 100% VAS (tolerance maximum). Intravenous electrostimulation as well as hyperosmolar solutions evoked pain in each subject. The intensity of pain was neither influenced by noradrenaline, nor by phentolamine, so that nociception from blood vessels is unlikely to be modulated by the sympathetic nervous system under physiological conditions in humans.
Kindgen-Milles
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Heinrich-Heine-Universität Düsseldorf, Institut für Experimentelle Anaesthesiologie, Germany.
Holthusen
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D000316:Adrenergic alpha-Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D000317:Adrenergic alpha-Antagonists / Q000008:administration & dosage / Q000494:pharmacology*; D004558:Electric Stimulation / Q000009:adverse effects; D006225:Hand / Q000098:blood supply; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D009638:Norepinephrine / Q000008:administration & dosage / Q000494:pharmacology; D009994:Osmolar Concentration; D010146:Pain / Q000188:drug therapy* / Q000209:etiology; D017288:Pain Threshold; D010646:Phentolamine / Q000008:administration & dosage / Q000494:pharmacology; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects* / Q000502:physiology; D012462:Saline Solution, Hypertonic / Q000008:administration & dosage / Q000009:adverse effects; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000502:physiology*; D014680:Veins / Q000187:drug effects*
D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D011942:Receptors, Adrenergic, alpha; D012462:Saline Solution, Hypertonic; D009638:Norepinephrine; D010646:Phentolamine