title: Effects of adenosine on intraocular pressure, optic nerve head blood flow, and choroidal blood flow in healthy humans.
abstract: OBJECTIVE
  There is evidence from a variety of animal studies that the adenosine system plays a role in the control of intraocular pressure (IOP) and ocular blood flow. However, human data on the effect of adenosine on IOP and choroidal and optic nerve blood flow are not available.
  
  
  METHODS
  The effect of stepwise increases in doses of adenosine (10, 20, and 40 micro g/kg per minute, 30 minutes per infusion step) on optic nerve head blood flow, choroidal blood flow, and IOP was determined in a placebo-controlled double-masked clinical trial in 12 healthy male volunteers. Blood flow in the optic nerve head and choroid was measured with laser Doppler flowmetry. In addition, fundus pulsation amplitude in the macula (FPAM) and the optic nerve head (FPAO) were assessed with laser interferometry.
  
  
  RESULTS
  Adenosine induced a small but significant decrease in IOP (at 40 microg/kg per minute: 12% +/- 13%), which was significant versus placebo (P = 0.046). In addition, adenosine induced a significant increase in choroidal blood flow (P < 0.001) and optic nerve head blood flow (P = 0.037), and FPAM (P = 0.0014) and tended to increase FPAO (P = 0.057). At the highest administered dose, the effect on choroidal hemodynamic parameters between 14% and 17%, whereas the effect on optic nerve hemodynamic parameters was between 3% and 11%.
  
  
  CONCLUSIONS
  These data are consistent with adenosine inducing choroidal and optic nerve head vasodilatation and reducing IOP in healthy humans. Considering the neuroprotective properties of adenosine described in previous animal experiments the adenosine system is an attractive target system for therapeutic approaches in glaucoma.
authors.affiliation: Department of Clinical Pharmacology, University of Vienna, Vienna, Austria.
authors.forename: Elzbieta
authors.initials: E
authors.lastname: Polska
authors.forename: Paulina
authors.initials: P
authors.lastname: Ehrlich
authors.forename: Alexandra
authors.initials: A
authors.lastname: Luksch
authors.forename: Gabriele
authors.initials: G
authors.lastname: Fuchsjäger-Mayrl
authors.forename: Leopold
authors.initials: L
authors.lastname: Schmetterer
mesh_terms: D000241:Adenosine / Q000494:pharmacology*; D000328:Adult; D001783:Blood Flow Velocity / Q000187:drug effects; D002829:Choroid / Q000098:blood supply*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D006801:Humans; D007368:Interferometry; D007429:Intraocular Pressure / Q000187:drug effects*; D017078:Laser-Doppler Flowmetry; D007834:Lasers; D008297:Male; D009898:Optic Disk / Q000098:blood supply*; D012039:Regional Blood Flow; D014664:Vasodilation; D014665:Vasodilator Agents / Q000494:pharmacology*
chemical_list: D014665:Vasodilator Agents; D000241:Adenosine