May 2008
Volume 49, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2008
Aqueous Humor Dynamics in the Mouse by Constant Flow Infusion
Author Affiliations & Notes
  • J. C. Millar
    Glaucoma Research, Alcon Research, Ltd., Fort Worth, Texas
  • I.-H. Pang
    Glaucoma Research, Alcon Research, Ltd., Fort Worth, Texas
  • A. F. Clark
    Glaucoma Research, Alcon Research, Ltd., Fort Worth, Texas
  • Footnotes
    Commercial Relationships  J.C. Millar, Alcon Research, Ltd., E; I. Pang, Alcon Research, Ltd., E; A.F. Clark, Alcon Research, Ltd., E.
  • Footnotes
    Support  None.
Investigative Ophthalmology & Visual Science May 2008, Vol.49, 354. doi:https://doi.org/
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    • Get Citation

      J. C. Millar, I.-H. Pang, A. F. Clark; Aqueous Humor Dynamics in the Mouse by Constant Flow Infusion. Invest. Ophthalmol. Vis. Sci. 2008;49(13):354. doi: https://doi.org/.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose: : We sought to measure intraocular pressure (IOP), outflow facility (C), and episcleral venous pressure (Pe), and deduce uveoscleral outflow (Fu) and aqueous formation rate (Fin), in the mouse eye.

Methods: : Adult male Balb/c mice were anesthetized. Resting IOP was determined (TonoLab). The anterior chamber was then cannulated (30G needle) and infused at constant flow rate (BSS-Plus®, 0.1-0.5µL/min, 0.1µL/min increments). Pressure developed was determined (pressure transducer). Clive was estimated from 1/(slope of regression line through Pressure-Flow Rate curve). Pe was estimated manometrically by lowering reservoir until Schlemm’s canal was observed to swell/redden (episcleral venous reflux). Animals were killed, eliminating Fin and Pe, and C determined again (Cdead). Fudead was deduced: Fudead = F-(IOPdead×Cdead), where F = perfusate flow rate. By assuming Fudead = Fulive, Fin was deduced: Fin = [(Clive×(IOP-Pe)]+Fudead.

Results: : In 4 control mice, anesthetized IOP was 9.9±0.3mmHg (mean±SEM, n=8 eyes). Clive was 0.011±0.0005µL/min/mmHg. Cdead was unchanged (0.011±0.001 µL/min/mmHg, P=0.8). Pe was 4.9±0.4mmHg. Fin was 0.081±0.018µL/min. Fu was 0.034±0.014µL/min (32.0±9.7% of Fin). In 7 mice, right eyes (OD) received 10µL Xalatan® (latanoprost, 0.005%) at 25, 19, & 1h prior to cannulation. Left eyes (OS) received vehicle (Veh). Xalatan reduced IOP from 11.1±0.5mmHg (Veh) to 7.7±0.3mmHg (P<0.001, n=7 eyes). Clive increased from 0.011±0.002µL/min/mmHg (Veh) to 0.015±0.002 µL/min/mmHg (P=0.012), and Pe decreased from 5.0±0.3mmHg (Veh) to 3.7±0.4mmHg (P=0.049). Fin did not significantly change (0.101±0.014µL/min with Veh vs 0.092±0.012µL/min with Xalatan), and neither did Fu (0.038±0.018µL/min, 32.5±11.0% of Fin with Veh vs 0.032±0.013µL/min, 35.2±9.3% of Fin with Xalatan). In 8 further mice, OD received 10µL Betoptic-S® (betaxolol HCl, 0.25%) at 25, 19, & 1h prior to cannulation. OS received Veh. Betaxolol reduced IOP from 13.4±0.6mmHg (Veh) to 8.2±0.4mmHg (P<0.001, n=8 eyes). Fin decreased from 0.166±0.022µL/min (Veh) to 0.091±0.016µL/min (P=0.009). Clive (0.018±0.002µL/min/mmHg with Veh vs 0.018±0.001 µL/min/mmHg with betaxolol), Pe (4.6±0.3mmHg with Veh vs 4.2±0.2mmHg with betaxolol), and Fu (0.015±0.008µL/min (5.3±3.6% of Fin) with Veh vs 0.020±0.010µL/min (15.1±7.9% of Fin) with betaxolol) were not significantly changed.

Conclusions: : Concurrent measurement of IOP, C, and Pe, and deduction of Fin and Fu, is feasible in the mouse eye. Xalatan lowers IOP by increasing C and reducing Pe. Betoptic-S lowers IOP by reducing Fin.Reference: Aihara, M., et al. IOVS 44: 5168-5173, 2003.

Keywords: aqueous • anterior chamber • inflow/ciliary body 
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