title: Obstructive apneic events induce alpha-receptor mediated digital vasoconstriction.
abstract: OBJECTIVE
  To characterize the role of alpha-receptors in autonomic control of digital skin blood flow change in response to obstructive apnea-hypopnea events.
  
  
  METHODS
  Experimental intervention study.
  
  
  METHODS
  Sleep laboratory in a university hospital.
  
  
  METHODS
  Eight male patients with severe obstructive sleep apnea (OSA).
  
  
  METHODS
  Patients received four cumulative dosage steps of phentolamine (0.066, 0.2, 2 and 5 [n=3] microg/min/100 ml forearm tissue) via brachial artery infusion during nonrapid eye movement sleep (stage 1 and 2).
  
  
  RESULTS
  The pulse amplitude determined with peripheral arterial tonometry (PAT) was periodically attenuated during the immediate post apnea-hypopnea period coinciding with arousal. PAT ratio (smallest pulse amplitude post apnea divided by largest pulse amplitude during apnea), was determined as a measure of digital vasoconstriction. We found that, compared with baseline, PAT ratio dose-dependently increased during phentolamine (0.2, 2 and 5 microg) infusion by 11.2+/-1.7%, 24.4+/-2.1% and 30.9+/-4.1%, respectively (P<0.001). Systemic blood pressure and heart rate were largely unaffected by the pharmacological intervention.
  
  
  CONCLUSIONS
  OSA related alteration of the pulse amplitude includes a constriction of digital skin vasculature that to a large extent is mediated via sympathoadrenergic alpha-receptors.
authors.affiliation: Sleep Laboratory, Pulmonary Medicine, Sahlgrenska University Hospital, Gothenburg, Sweden.
authors.forename: Ding
authors.initials: D
authors.lastname: Zou
authors.forename: Ludger
authors.initials: L
authors.lastname: Grote
authors.forename: Derek N
authors.initials: DN
authors.lastname: Eder
authors.forename: Yüksel
authors.initials: Y
authors.lastname: Peker
authors.forename: Jan
authors.initials: J
authors.lastname: Hedner
mesh_terms: D000317:Adrenergic alpha-Antagonists / Q000008:administration & dosage / Q000494:pharmacology; D000328:Adult; D001794:Blood Pressure / Q000187:drug effects; D015992:Body Mass Index; D004569:Electroencephalography; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007269:Injections, Intra-Arterial; D008297:Male; D008875:Middle Aged; D010646:Phentolamine / Q000008:administration & dosage / Q000494:pharmacology; D017286:Polysomnography; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects* / Q000378:metabolism*; D012815:Signal Processing, Computer-Assisted; D012891:Sleep Apnea Syndromes / Q000378:metabolism / Q000503:physiopathology; D020181:Sleep Apnea, Obstructive / Q000378:metabolism* / Q000503:physiopathology*; D012894:Sleep Stages / Q000187:drug effects; D014661:Vasoconstriction / Q000187:drug effects*
chemical_list: D000317:Adrenergic alpha-Antagonists; D011942:Receptors, Adrenergic, alpha; D010646:Phentolamine