Physical factors affecting outflow facility measurements in mice

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Title: Physical factors affecting outflow facility measurements in mice
Author(s): Boussommier-Calleja, A
Li, G
Wilson, A
Ziskind, T
Scinteie, OE
Ashpole, NE
Sherwood, JM
Farsiu, S
Challa, P
Gonzalez, P
Downs, JC
Ethier, CR
Stamer, WD
Overby, DR
Item Type: Journal Article
Abstract: Purpose: Mice are commonly used to study conventional outflow physiology. This study examined how physical factors (hydration, temperature, and anterior chamber [AC] deepening) influence ocular perfusion measurements in mice. Methods: Outflow facility (C) and pressure-independent outflow (Fu) were assessed by multilevel constant pressure perfusion of enucleated eyes from C57BL/6 mice. To examine the effect of hydration, seven eyes were perfused at room temperature, either immersed to the limbus in saline and covered with wet tissue paper or exposed to room air. Temperature effects were examined in 12 eyes immersed in saline at 20°C or 35°C. Anterior chamber deepening was examined in 10 eyes with the cannula tip placed in the anterior versus posterior chamber (PC). Posterior bowing of the iris (AC deepening) was visualized by three-dimensional histology in perfusion-fixed C57BL/6 eyes and by spectral-domain optical coherence tomography in living CD1 mice. Results: Exposure to room air did not significantly affect C, but led to a nonzero Fu that was significantly reduced upon immersion in saline. Increasing temperature from 20°C to 35°C increased C by 2.5-fold, more than could be explained by viscosity changes alone (1.4-fold). Perfusion via the AC, but not the PC, led to posterior iris bowing and increased outflow. Conclusions: Insufficient hydration contributes to the appearance of pressure-independent outflow in enucleated mouse eyes. Despite the large lens, AC deepening may artifactually increase outflow in mice. Temperature-dependent metabolic processes appear to influence conventional outflow regulation. Physical factors should be carefully controlled in any outflow studies involving mice.
Publication Date: 1-Dec-2015
Date of Acceptance: 5-Nov-2015
URI: http://hdl.handle.net/10044/1/43520
DOI: http://dx.doi.org/10.1167/iovs.15-17106
ISSN: 1552-5783
Publisher: Association for Research in Vision and Ophthalmology
Start Page: 8331
End Page: 8339
Journal / Book Title: Investigative Ophthalmology & Visual Science
Volume: 56
Issue: 13
Copyright Statement: © 2016 The Association for Research in Vision and Ophthalmology, Inc
Keywords: Science & Technology
Life Sciences & Biomedicine
Ophthalmology
trabecular meshwork
glaucoma
mouse models
intraocular pressure
Schlemm's canal
AQUEOUS-HUMOR DYNAMICS
ENUCLEATED HUMAN EYES
INTRAOCULAR-PRESSURE
TRABECULAR MESHWORK
CILIARY MUSCLE
MOUSE EYES
PILOCARPINE
RESISTANCE
MECHANISM
PERFUSION
Animals
Anterior Chamber
Aqueous Humor
Eye Enucleation
Female
Imaging, Three-Dimensional
Intraocular Pressure
Male
Mice
Mice, Inbred C57BL
Tomography, Optical Coherence
Trabecular Meshwork
Anterior Chamber
Aqueous Humor
Trabecular Meshwork
Animals
Mice, Inbred C57BL
Mice
Imaging, Three-Dimensional
Tomography, Optical Coherence
Eye Enucleation
Intraocular Pressure
Female
Male
Ophthalmology & Optometry
11 Medical And Health Sciences
06 Biological Sciences
Publication Status: Published
Appears in Collections:Bioengineering
Faculty of Natural Sciences



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