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J Cameron Millar, Navita N Lopez, Urmimala Raychaudhuri, Abbot F. Clark; Mouse Eye Perfusion In-Vivo Versus Ex-Vivo: Influence on Aqueous Outflow Facility. Invest. Ophthalmol. Vis. Sci. 2018;59(9):1655.
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© ARVO (1962-2015); The Authors (2016-present)
In live mouse eyes perfused via the anterior chamber (AC) or posterior chamber (PC), the relationship between flow rate (FR) and pressure (P) approaches linearity over the FR range 100-500nL/min and aqueous outflow facility (C) is not significantly different. But others have reported that in enucleated mouse eyes perfused via the AC, a combination of a pupil block, iris bowing and posterior iris-ciliary body excursion leads to an increase in C (becoming more pronounced as FR increases), yielding a non-linear relationship between FR and C. But in enucleated eyes perfused via the PC, C is very low. Here we compared C via both AC and PC perfusion, in both live and enucleated mouse eyes.
C57BL/6J mice (♀, 45-49 wks.) were divided into 4 groups (8 animals/group). Groups 1 and 2 were anesthetized (ketamine 100 mg/kg; xylazine 10 mg/kg). Right eyes were cannulated (30G needle, Group 1 (AC); Group 2 (PC)) and C was measured (constant flow infusion). To investigate effect of enucleation, mice in Groups 3 and 4 were euthanized (100% CO2) and their right eyes removed and placed in wells filled with saline. Eyes were then cannulated via the AC (Group 3) or PC (Group 4) and constant flow infusion commenced within 60 min.
Over the FR range 100-500nL/min, C in Groups 1 and 2 was 24.8±2.7 vs. 25.6±1.1nL/min/mmHg, respectively (mean±SEM, p=0.8049, N/S). The relationship between P and FR approached linearity. When FR was increased (600-800nL/min), P climbed progressively more steeply and the linear relationship broke down. In Group 3 the relationship between P and FR (100-800nL/min) exhibited a sigmoidal relationship (11.8 ≤ C ≤ 61.5nL/min/mmHg). In Group 4 the relationship between P and FR was close to linear but C was low compared with live eyes (6.0±0.2nL/min/mmHg, p<0.00001).
The relationship between FR and C in living mice approaches linearity when 100nL/min ≤ FR ≤ 500nL/min. AC or PC perfusion does not lead to a significantly different value for C. When FR ≥ 600nL/min, C decreases (up to FR=800nL/min). In enucleated eyes perfused via the AC, the relationship between C and FR is sigmoidal, and C increases with increasing FR (from 100nL/min to 800nL/min). In enucleated eyes perfused via the PC, C is very low when 100nL/min ≤ FR ≤ 800nL/min. Perfusion of live or enucleated mouse eyes leads to qualitatively different values for C.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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