Abstract
Purpose:
To describe voltage-coupled single-needle constant-pressure anterior chamber perfusion in live mice
Methods:
We established apparatus in which transduced pressure was coupled to a microperfusion pump to automatically modulate flow rate to maintain a steady pressure and measure outflow facility by constant pressure perfusion. All perfusion was performed by 35G single-needle anterior chamber cannulation in anesthetized mice. We characterized the following: (i) perfusion pressure stability; (ii) outflow facility; (iii) presence of “washout”; (iv) effect of different perfusates such as phosphate buffered saline with Ca2+and Mg2+ (PBS w Ca/Mg), PBS without Ca/Mg (PBS w/o Ca/Mg), and Barany’s solution. H&E staining was performed on frozen sections following perfusions.
Results:
Twenty nine live C57BL/6 mice underwent perfusion. Constant pressure was attained within seconds, stably maintained, and not significantly affected by different perfusates (p>0.05). Relationship between flow rate and pressure fit a linear function for perfusion between 15-35mmHg (R2>0.9). Outflow facility determined by 1-level constant pressure perfusion was similar irrespective of perfusate (p>0.5): 0.0095 μl/min*mmHg for PBS w Ca/Mg (n=10); 0.0123 μl/min*mmHg for PBS w/o Ca/Mg (n=10); 0.0074 μl/min*mmHg for Barany’s solution (n=9). Needle resistance was negligible relative to physiologically relevant perfusion. 2-level constant pressure perfusion over 2 hours showed no washout phenomenon. Histological disruption of drainage tissue following perfusions was not seen.
Conclusions:
Stable constant pressure perfusion under physiologically relevant conditions was achieved by perfusion using single-needle cannulation, which is well-suited to the tiny mouse eye. The washout phenomenon was not seen. Our methods are potentially applicable to live mouse studies.
Keywords: 633 outflow: trabecular meshwork •
735 trabecular meshwork