title: The effect of sodium nitroprusside on cerebral hemodynamics and headache in healthy subjects.
abstract: METHODS
  Sodium nitroprusside (SNP) is a powerful vasodilatory agent that, similarly to glyceryl trinitrate (GTN), releases nitric oxide (NO) but in contrast does not pass the blood-brain barrier. Nevertheless, it has already been used in animal models without any knowledge of its headache-inducing potential. We hypothesized that SNP would induce headache and vasodilation of cephalic and radial but not cerebral arteries.
  
  
  METHODS
  Five healthy volunteers received intravenous infusions of SNP in a non-randomized dose-titration (1-5 µg/kg/min) study. We recorded headache intensity (verbal rating scale from 0 to 10), velocity in the middle cerebral artery (VMCA), and diameters of the superficial temporal artery (STA) and radial artery (RA).
  
  
  RESULTS
  All participants reported a dose-related headache (median peak = 2.5, range 0-3). SNP dilated the STA and RA, caused a marked increase of heart rate and a decrease of mean arterial pressure (MAP) and partial pressure of end-tidal carbon dioxide (PetCO2). We found that SNP decreased the velocity of the VMCA, but this was canceled by a decrease of cerebral blood flow (CBF) due to hypocapnia.
  
  
  CONCLUSIONS
  The present study shows that SNP is a headache-inducing agent with close similarities to headaches induced by GTN and probably without effect on intracerebral arteries.
authors: Danish Headache Center and Department of Neurology, Glostrup Hospital, Faculty of Health Sciences, University of Copenhagen, Denmark.
authors: Song
authors: S
authors: Guo
authors: Messoud
authors: M
authors: Ashina
authors: Jes
authors: J
authors: Olesen
authors: Steffen
authors: S
authors: Birk
mesh_terms: D000328:Adult; D001794:Blood Pressure / Q000187:drug effects; D001921:Brain / Q000098:blood supply / Q000187:drug effects; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006261:Headache / Q000139:chemically induced*; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D008297:Male; D009599:Nitroprusside / Q000008:administration & dosage / Q000009:adverse effects*; D014665:Vasodilator Agents / Q000008:administration & dosage / Q000009:adverse effects*; D055815:Young Adult
chemical_list: D014665:Vasodilator Agents; D009599:Nitroprusside