Effect of DMSO and exchange volume on outflow resistance washout and response to pilocarpine during anterior chamber perfusion in monkeys.
OBJECTIVE
To determine the dependence of outflow resistance washout on anterior chamber (AC) fluid exchange volume (EV); the minimum EV required for complete AC mixing, and the effect of 0.01-5% DMSO in the exchange solution on outflow resistance.


METHODS
Total outflow facility was determined in 63 pentobarbital-anesthetized cynomolgus monkeys, before and after AC exchange, for 10 min, with 1, 2, and 4 ml of Bárány's perfusand, containing 0.01-5% DMSO or containing 1 microgram/ml or 5 micrograms/ml pilocarpine HCL (pilo), each volume.


RESULTS
Post-exchange facility increased by 21% (p < 0.05) vs. baseline for both the 1 and 2 ml Bárány's volumes and by 50% (p < 0.001) for the 4-ml volume. Washout-corrected post-exchange facility was unchanged from baseline, following 1 or 2 ml exchange with 1 microgram/ml pilo; 5 micrograms/ml pilo increased facility by 130 +/- 41% and 174 +/- 40% respectively, relative to baseline. Exchange with 4 ml of 1 microgram/ml pilo increased facility 72% more than the 2 ml (p < 0.029) and 100% more than the 1 ml (p < 0.014) volumes. When corrected for their respective baselines, 2 ml of 5 micrograms/ml pilo increased facility 12.7 +/- 4.4% more than the 1 ml volume (p < 0.05). Post exchange facility was not significantly increased over baseline in eyes exchanged with 2 ml of 0.01-4% DMSO or in eyes exchanged with Bárány's alone. When corrected for their respective baselines, post-exchange facility was significantly lower in eyes exchanged with 5% DMSO vs. Bárány's (p = 0.022).


CONCLUSIONS
One- and 2-ml EVs preserve outflow resistance equally well, and substantially better than 4 ml. Two ml is the minimum volume necessary for adequate mixing of AC drug solutions, to achieve the full facility effect. Concentrations of DMSO up to 4% in a 2-ml EV can solubilize compounds without additionally decreasing outflow resistance.
Kiland
J A
JA
Department of Ophthalmology and Visual Sciences, University of Wisconsin, Madison 53792-3220, USA. jkiland@facstaff.wisc.edu
Peterson
J A
JA
Gabelt
B T
BT
Kaufman
P L
PL
D000818:Animals; D000867:Anterior Chamber / Q000502:physiology*; D001082:Aqueous Humor / Q000187:drug effects* / Q000502:physiology*; D004121:Dimethyl Sulfoxide / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D008252:Macaca fascicularis; D008297:Male; D010477:Perfusion; D010862:Pilocarpine / Q000494:pharmacology*
D010862:Pilocarpine; D004121:Dimethyl Sulfoxide