title: The direct effects of propofol on pial microvessels in rabbits.
abstract: Propofol is widely used for neurosurgical anesthesia; however, its effects on the pial microvasculature are unknown. We therefore evaluated the direct effects of propofol on pial microvessels in rabbits. Pial microcirculation was visualized using a closed cranial window technique in 20 Japanese white rabbits. In the first experiment (n=14), after baseline hemodynamic measurements, the cranial window was superfused with 5 increasing concentrations of propofol (10, 10, 10, 10, 10 mol/L; n=8) or intralipid (at comparable concentrations; n=6) dissolved in artificial cerebrospinal fluid for 7 minutes each. A typical anesthetic concentration of 5 microg/mL corresponds to 10 mol/L. In the second experiment (n=6), phenylephrine 10 mol/L and nitroglycerin 10 mol/L were applied topically for 7 minutes under pentobarbital anesthesia. In the third experiment (n=3), electroencephalogram and bispectral index were measured under pentobarbital anesthesia. Diameters of selected pial arterioles and venules were visualized with a microscope-video capture unit combination and subsequently measured with a digital video analyzer. Topical application of propofol at 10, 10, 10, or 10 mol/L did not alter the diameters of the pial microvessels; however, at 10 mol/L propofol induced dilation in large and small arterioles, along with venular dilation. Intralipid alone did not have any significant effect on vessel diameters. Phenylephrine and nitroglycerin produced pial arteriolar and venular constriction and dilation, respectively. Phenylephrine constricted and nitroglycerin dilated pial arterioles and venules. Pentobarbital did not produce either burst suppression or an isoelectric electroencephalogram. The results confirm our hypothesis: clinically relevant concentrations of propofol, that is, approximately 10 mol/L, do not dilate pial arterioles or venules.
authors.affiliation: Department of Anesthesiology, Faculty of Medicine, University of Yamanashi, Yamanashi, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Shibuya
authors.forename: Tadahiko
authors.initials: T
authors.lastname: Ishiyama
authors.forename: Manabu
authors.initials: M
authors.lastname: Ichikawa
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Sato
authors.forename: Katsumi
authors.initials: K
authors.lastname: Okuyama
authors.forename: Daniel I
authors.initials: DI
authors.lastname: Sessler
authors.forename: Takashi
authors.initials: T
authors.lastname: Matsukawa
mesh_terms: D018686:Anesthetics, Intravenous / Q000494:pharmacology*; D000818:Animals; D001160:Arterioles / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects; D001831:Body Temperature / Q000187:drug effects; D001835:Body Weight / Q000187:drug effects; D002196:Capillaries / Q000187:drug effects; D002550:Cerebral Veins / Q000187:drug effects; D004569:Electroencephalography; D005217:Fat Emulsions, Intravenous / Q000494:pharmacology; D006339:Heart Rate / Q000187:drug effects; D005996:Nitroglycerin / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D010841:Pia Mater / Q000098:blood supply*; D015742:Propofol / Q000494:pharmacology*; D011817:Rabbits; D012039:Regional Blood Flow / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology; D014699:Venules / Q000187:drug effects
chemical_list: D018686:Anesthetics, Intravenous; D005217:Fat Emulsions, Intravenous; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D010656:Phenylephrine; D005996:Nitroglycerin; D015742:Propofol