title: Effect of adenosine on cerebral blood flow velocity.
abstract: OBJECTIVE
  Evidence suggests that adenosine (ADN) is a potent vasodilator of cerebral vessels. However, the feasibility of manipulating human cerebral vascular resistance with ADN has not been assessed by means of TCD. The purpose of this study was to quantitatively estimate the change in middle cerebral artery cerebral blood flow velocity (CBFV) in response to intravenous ADN infusion in humans.
  
  
  METHODS
  Eleven patients with subacute cerebrovascular events (ischemic stroke, transient ischemic attack, or hemorrhage) undergoing adenosine-thallium stress testing were studied before, during, and after ADN infusion to evaluate the effect of ADN on cerebral blood flow velocity. Continuous blood pressure (BP), heart rate (HR), respiration rate (RR), end-tidal CO2 (ET-CO2), and transcranial Doppler ultrasonography monitoring of CBFV and pulsatility index (PI) in both middle cerebral arteries were performed.
  
  
  RESULTS
  The mean CBFVs were 65.4 +/- 19.2 cm/s before, 55.4 +/- 18.1 cm/s during, and 64.1 +/- 22.5 cm/s after ADN infusion, which represents a statistically significant decrease during ADN test compared with both baseline (P = .007) and posttest levels (P = .017). The PI was increased during the test (0.91 +/- 0.2) when compared with baseline (0.71 +/- 0.1) (P = .007). During ADN injection, mean HR increased (P = .004) and mean ET-CO2 levels decreased significantly (P = .003). Mean BP and RR did not change significantly.
  
  
  CONCLUSIONS
  The authors hypothesize that any direct vasodilatory effect of ADN on the distal cerebral peripheral vasculature may be negated by an effect of ADN on depth of respiration resulting in hypocapnia and secondary distal vasoconstriction.
authors.affiliation: Institute of Neurology, University of Parma, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Zanferrari
authors.forename: A Y
authors.initials: AY
authors.lastname: Razumovsky
authors.forename: P M
authors.initials: PM
authors.lastname: Lavados
authors.forename: S
authors.initials: S
authors.lastname: Sen
authors.forename: S M
authors.initials: SM
authors.lastname: Oppenheimer
mesh_terms: D000241:Adenosine / Q000494:pharmacology*; D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D001783:Blood Flow Velocity / Q000187:drug effects*; D001794:Blood Pressure / Q000502:physiology; D002245:Carbon Dioxide / Q000378:metabolism; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D002561:Cerebrovascular Disorders / Q000000981:diagnostic imaging / Q000503:physiopathology*; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D008875:Middle Aged; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging / Q000187:drug effects*; D011446:Prospective Studies; D011673:Pulsatile Flow; D017585:Ultrasonography, Doppler, Transcranial; D014665:Vasodilator Agents / Q000494:pharmacology*
chemical_list: D014665:Vasodilator Agents; D002245:Carbon Dioxide; D000241:Adenosine