Abstract
Abstract: :
Purpose: To determine if H–7 can increase outflow facility in monkey organ cultured anterior segments and if the response is reversible. Methods: Rhesus and cynomolgus monkey paired anterior segments with iris and uvea removed were glued onto organ culture dishes and perfused with DMEM at a constant rate of 2.5µl/min. Following overnight equilibration, baseline outflow facility was determined by two–level constant pressure perfusion. One segment of each pair was then exchanged with 300µM H–7, then H–7 infusion at 2.5µl/min was continued overnight. Post–treatment outflow facility was monitored at various times after treatment and daily after returning to plain media infusion. Some segments that returned to baseline were treated a second time with H–7 and the measurements repeated. Results:Baseline outflow facility (µl/min/mmHg) was no different between the paired eyes, and averaged (mean±sem) 0.42±0.07 (n=7). In most cases (4 of 6), the H–7 – induced outflow facility increase did not start until 1 or 2 days after the initial exchange and remained elevated for several days. When all eyes were considered, the mean maximum outflow facility increase was 242±90% (n=7, p<0.05), occurring 2 hr to 5 days after treatment. Six of seven segments that responded to H–7 returned to baseline by 1–3 days after returning to plain media infusion. Two of these segments were again exchanged with 300µM H–7. Outflow facilities were increased in both treated eyes one day later: one eye was increased more than before; the other was increased less than before. Outflow facility calculated from the constant rate method gave similar but more variable results, probably due to the lower starting pressures in the monkey preparation than typically found in the human eye preparation. Conclusions:H–7 increases outflow facility in the monkey anterior segment organ culture system at a dose found to be effective in monkeys in vivo. However, the response was much slower to develop than in vivo. The in vitro system outflow facility recovered to baseline after several days and could be stimulated again.
Keywords: anterior segment • cytoskeleton • outflow: trabecular meshwork