Purchase this article with an account.
Teresa Borrás, Laura Leigh S. Rowlette, Ernst R. Tamm, Johannes Gottanka, David L. Epstein; Effects of Elevated Intraocular Pressure on Outflow Facility and TIGR/MYOC Expression in Perfused Human Anterior Segments. Invest. Ophthalmol. Vis. Sci. 2002;43(1):33-40.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
purpose. To investigate the effects of high intraocular pressure (h-IOP) on TIGR/MYOC expression, extracellular matrix (ECM) deposition,
and outflow facility (C) in perfused human anterior
methods. Anterior segments of 31 pairs of normal human eyes from postmortem
donors were perfused at constant flow (3 μl/min). After reaching
stable baseline, the flow of one eye from each of 31 pairs was raised
to obtain a continuous pressure of 60 to 70 mm Hg for a period of 1
hour (3 pairs), 6 hours (10 pairs), 24 hours (2 pairs), 48 hours (3
pairs), and 7 days (13 pairs). Sixteen of these pairs were used to
study trabecular meshwork expression of TIGR/MYOC and
stromelysin by Northern blot analysis hybridization. Nine pairs (1 pair
each at h-IOP for 1, 6, and 48 hours and 6 pairs at 7 days) were fixed
at pressure for analysis by electron microscopy. Eyes selected for C measurements fulfilled the inclusion criteria of C 0 values between 0.06 and 0.4, intact RNA
recovery and normal light microscopy morphology. Percent change of
facility from the baseline (C/C 0) was
computed at 6 and 24 hours and 2, 4, and 7 days from the long-term
perfusion experiments (n = 9 h-IOP, n = 8 controls).
results. No induction of TIGR/MYOC expression was observed after
h-IOP for 1 and 6 h. A slight induction was seen after 24 and 48
hours. At 7 days, the treated eye from 4 of 5 pairs showed a clear
induction, which was very pronounced in one of the pairs. In contrast,
stromelysin expression was induced at 6 hours and not at 7 days.
Morphometric electron microscopy after 7 days showed no significant
difference in the amounts of fine fibrillar material or plaque material
in the juxtacanalicular (JCT) region. The percent increase of C of the treated eye at 6 hours was 11.0% ± 4.6%
compared with 3.7% ± 3.8% in the control eyes (P = 0.26). However, after longer time periods, the facility of the h-IOP
eyes increased, whereas that of the contralateral eyes remained
unchanged. This difference reached peak, significant values at 4 days
(32.9% ± 8.4% versus 7.4% ± 7.6%, respectively; P = 0.04) and decreased to 8.9% ± 7.9% versus
1.1% ± 12.7% (P = 0.6) at 7 days.
conclusions. Elevated IOP appears to cause a decrease in outflow pathway resistance
at 1 to 4 days, and this effect seems to disappear with further time.
In contrast, induction of TIGR/MYOC appears to be strongest
at 7 days. We speculate that this induction pattern might indicate a
stress-related, rather than a possible homeostatic, role for the
This PDF is available to Subscribers Only