title: The feasibility of intracarotid adenosine for the manipulation of human cerebrovascular resistance.
abstract: To assess the feasibility of manipulating human cerebrovascular resistance with adenosine, we measured cerebral blood flow (CBF) by determining the initial slope (IS) of tracer washout 20-80 s after intracarotid 133Xe injection (standard IS) during sequential 3-min intracarotid infusions of (a) saline; (b) adenosine 1.2-mg bolus followed by an infusion of 1 mg/min (bolus + infusion); (c) saline; and (d) nicardipine (0.1 mg/min). During 133Xe washout, adenosine caused a rapidly clearing compartment. Therefore, tracer washout was also analyzed 5-25 s after injection (early IS). Nicardipine (n = 8) increased both standard IS (from 39+/-12 to 53+/-16 mL 100g.min(-1); P < 0.005) and early IS (from 40+/-9 to 55+/-20 arbitrary units; P < 0.02) to a similar degree. Adenosine bolus + infusion increased early IS (from 33+/-6 to 82+/-43 arbitrary units; P < 0.02) but did not increase standard IS (from 41+/-12 to 43 +/-16 mL 100g(-1) min(-1)). Standard and early IS values were then determined before and after adenosine delivered either by infusion alone (2 mg/min for 3 min, n = 5) or bolus alone (2 mg in 1 s, n = 3). Neither standard nor early IS changed after adenosine infusion alone. Early IS increased after adenosine bolus alone. Increase in early IS, but not standard IS, suggests a transient (<30 s) increase in CBF.
  
  
  CONCLUSIONS
  Intracarotid adenosine, in the 1- to 2-mg dose range, may cause a transient, but not a sustained, increase in cerebral blood flow. Intracarotid adenosine in such a dose range does not seem to be an appropriate drug for sustained manipulation of cerebrovascular resistance.
authors.affiliation: Department of Anesthesiology, College of Physicians and Surgeons, Columbia University, New York, New York 10032, USA.
authors.forename: S
authors.initials: S
authors.lastname: Joshi
authors.forename: W L
authors.initials: WL
authors.lastname: Young
authors.forename: J
authors.initials: J
authors.lastname: Pile-Spellman
authors.forename: D H
authors.initials: DH
authors.lastname: Duong
authors.forename: M C
authors.initials: MC
authors.lastname: Vang
authors.forename: L
authors.initials: L
authors.lastname: Hacein-Bey
authors.forename: H T
authors.initials: HT
authors.lastname: Lee
authors.forename: N
authors.initials: N
authors.lastname: Ostapkovich
mesh_terms: D000241:Adenosine / Q000494:pharmacology*; D000328:Adult; D000368:Aged; D002343:Carotid Artery, Internal; D002533:Cerebral Angiography; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D005260:Female; D006801:Humans; D007261:Infusions, Intra-Arterial; D008297:Male; D008875:Middle Aged; D009529:Nicardipine / Q000494:pharmacology; D014655:Vascular Resistance / Q000187:drug effects*; D014665:Vasodilator Agents / Q000494:pharmacology*; D014980:Xenon Radioisotopes
chemical_list: D014665:Vasodilator Agents; D014980:Xenon Radioisotopes; D009529:Nicardipine; D000241:Adenosine