title: Pharmacological MRI of the choroid and retina: blood flow and BOLD responses during nitroprusside infusion.
abstract: Nitroprusside, a vasodilatory nitric oxide donor, is clinically used during vascular surgery and to lower blood pressure in acute hypertension. This article reports a novel application of blood flow (BF) and blood oxygenation level dependent (BOLD) MRI on an 11.7T scanner to image the rat chorioretinal BF and BOLD changes associated with graded nitroprusside infusion. At low doses (1 or 2 μg/kg/min), nitroprusside increased BF as expected but decreased BOLD signals, showing an intriguing BF-BOLD uncoupling. At high doses (3-5 μg/kg/min), nitroprusside decreased BF and markedly decreased BOLD signals. To our knowledge, this is the first pharmacological MRI application of the retina. This approach has potential to open up new avenues to study the drug-related hemodynamic functions and to evaluate the effects of novel therapeutic interventions on BOLD and BF in the normal and diseased retinas.
authors.affiliation: Research Imaging Institute, University of Texas Health Science Center, San Antonio, Texas 78229, USA. shihy@uthscsa.edu
authors.forename: Yen-Yu I
authors.initials: YY
authors.lastname: Shih
authors.forename: Guang
authors.initials: G
authors.lastname: Li
authors.forename: Eric R
authors.initials: ER
authors.lastname: Muir
authors.forename: Bryan H
authors.initials: BH
authors.lastname: De La Garza
authors.forename: Jeffrey W
authors.initials: JW
authors.lastname: Kiel
authors.forename: Timothy Q
authors.initials: TQ
authors.lastname: Duong
mesh_terms: D000818:Animals; D001783:Blood Flow Velocity / Q000187:drug effects; D002829:Choroid / Q000187:drug effects* / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D007261:Infusions, Intra-Arterial; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009599:Nitroprusside / Q000008:administration & dosage*; D010100:Oxygen / Q000097:blood*; D051381:Rats; D020318:Rats, Long-Evans; D012160:Retina / Q000187:drug effects* / Q000502:physiology*; D014665:Vasodilator Agents / Q000008:administration & dosage
chemical_list: D014665:Vasodilator Agents; D009599:Nitroprusside; D010100:Oxygen