Download Pattern of ocular response to topical and systemic

36
Inocstigatioc Ophthalmology
January 1975
Reports
terior or iris processes and in the posterior ciliary
processes.
Discussion. Horseradish peroxidase is an acceptable tracer for plasma protein since it retains
its molecular weight of about -40,000 daltons, corresponding to a molecular diameter of 45 A, after
it is injected intravenously into laboratory
animals.7 The results of our experiments, then,
support the hypothesis, either directly or indirectly, that prostaglandin E.: causes changes in
the tight junctions that seal the lateral intercellular clefts of the noiipigineiited epithelium of
the ciliary processes in the rabbit eye."' We believe
that the passage of tracer protein demonstrated
in this study indicates that in response to prostaglandin E.., plasma proteins puss from the stroma
of the ciliary processes into the posterior chamber
via the intercellular clefts of the nonpigmeiited
epithelium. Ellorts are in progress to determine
whether the change in patency of the tight junctions is a direct action of prostaglandins or merely
a result of increased hydrostatic pressure within
the ciliary processes.
While this manuscript was in press, Tamuras
suggested that in response to prostaglandins, increased transport of Thorotrast occurred across
the nonpigmeiited epithelium by membrane-bound
vesicles and indicated this route for the entry ol
protein into the posterior chamber. In our studies
with peroxidase, a smaller molecule than Thorotrast, an insignificant number of peioxidase-containing vesicles was observed.
We thank Barbara Brown, Eva Eugenes, and
Robyn Rufner for technical assistance.
From the Department of Ophthalmology and
Visual Science, Yale University School of Medicine,
New Haven, Conn. This work was supported in
part by United States Public Health Service
Grants Nos. EY-00237 and EY-00785 and the
John A. Hartford Foundation, Inc. Submitted
for publication June 17, 1974. Reprint requests:
Dr. A. H. Neufeld, Yale University School of
Medicine, 333 Cedar St., New Haven, Conn.
06510.
Key words: ciliary body, blood-aqueous barrier,
prostaglandins, rabbit, horseradish peroxidase.
REFERENCES
1. Shiose, Y.: Electron microscopic studies on
blood-retinal and blood-aqueous barriers, Jap.
). Ophthalmol. 14: 73, 1970.
2. Vegge, T.: An epithelial blood-aqueous barrier to horseradish peroxidase in the ciliary
processes of the vervet monkey (Ccrcopithccus
aethiops), Z. Zellforsch. 144: 309, 1971.
3. Uusitalo, R., Palkama, A., and Stjernschantz,
|.: An electron microscopical study of the
blood-aqueous barrier in the ciliary body and
iris of the rabbit, Exp. Eye Res. 17: 49, 1973.
4. Neufeld, A. H., Jampol, L. M., and Sears,
M. L.: Aspirin prevents the disruption of the
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5.
6.
7.
8.
blood-aqueous barrier in the rabbit eye,
Nature 238: 158, 1972.
Neufeld, A. H., and Sears, VI. L.: The site of
action of prostaglandin E; on the disruption of
the blood-aqueous barrier in the rabbit eye,
E.vp. Eye Res. 17: 445, 1973.
dementi, F., and Palade, C. E.: Intestinal
capillaries. I. Permeability to peroxidase and
ferritin, |. Cell Biol. 41: 33, 1969.
Vegge, T., Whither, F. O., and Olsen, B. R.:
Horseradish peroxidase in plasma studied by
gel infiltration, Histochemie 28: 16, 1971.
Tanuira, T.: Effects of prostaglandin Ei and
E.. on the ciliary body of albino rabbits: an
electron microscopic study, fap. f. Ophthalmol.
18: 135, 1974.
Pattern of ocular response to topical and
systemic prostaglandin. KEITH GREEN AND
KEUN KIM.
Changes i)i hotli intraocular pressure and total
outflow facility were determined after short- and
long-term infusion and topical application of prostaglandin E, and E\. The intraocular pressure with
both routes of administration increased within 15
minutes hy 10 to 15 mm. Hg; long-term infusion
caused the intraocular pressure to he elevated for
a longer time, although a fall in intraocular pressure occurred despite continued infusion. Total
outflow facility did not increase until 30 minutes
after initiation of treatment and thereafter increased further with time, irrespective of the route
of drug application. The initial, increase, in intraocular pressure is suggested to he the result, of
vascular changes, namely an increase in the leakiness of the iris vessels and the capillary pressure
of the ciliary body vessels caused by the vasodilatory acrtions of prustaglandins.
Prostaglandins (PC) are known to induce an
e l e v a t i o n ol i n t i a o e u l a r
pie.ssunj w h e n
given
inlra-
caineially, 1 topically,-- :| or intravenously. 1 The
ellects on total outflow facility, however, have
not been well documented. Topical application ol
PC-precursor, aiachidonic acid, or PCE, and
PCE.. is known to increase outllow facility 30
minutes alter application ol the drug."1 lntracameral injection of PC produces a nonstatisticallv
significant increase in total outllow facility.1 Inlravenous PC infusion has been reported not to increase total outllow laeility, 1 although the measurement was made at a time when the- intraocular
pressure was at a peak, viz, within 10 minutes ol
the initiation ol the infusion. The piesent .study
was made to examine the time course ol cllect ol
topical and systemic PC's on intraocular pressure
and outllow lacility of the rabbit eye in order to
clarify the initial phase of prostaglandin ellects in
the eye.
Reports 37
Volume 14
Nuwlx'r 1
Table F. Total outflow facility of I lie rabbit eye during intravenous infusion or topical
application of prostaglandins
Time (minutes)
PC.
Prc-ilnii
PCE,
0.165
±0.013
0.170
±0.011
0.182
±0.007
0.178
±0.007
0.174
±0.009
0.176
±0.011
Route
60 minutes intravenous
PCE,
10 minutes intravenous
PCE,
PCE..
PCE,
Topical
PCE,.
30
10
0.191"
±0.005
0.17211
±0.010
0.1 S311
±0.009
0.196 i;
±0.011
0.189"
±0.014
0.196'
±0.008
0.210 >
±0.019
0.222 : '
±0.027
0.200"°
±0.012
—
0.315"
±0.020
0.2771
±0.024
60
0.289±0.031
0.293±0.028
0.261'
±0.016
0.284'
±0.015
0.355 •
±0.030
0.366'
90
N
—
6
—
6
0.361'
±0.017
0.368'
±0.028
—
12
6
6
6
±0.021
T h e p i e - i l r u H p h a s e f o r t h e ( i ( ) - i i i n i u t e i n t i a v e n o i i s i n j e c t i o n of I ' G l i , a n d l ' G l i : w a s a 3 0 - i n i n u t e i n f u s i o n of v e h i c l e a l o n e
w i t h C m d e t e i m i n e d d i n i n g t h e last t h r e e m i n u t e s of t h a t p e r i o d . I ' m o t h e r l i m e s a n i l m o d e s of a d m i n i s t r a t i o n , t h e p r e d n i n C i m w a s d e t e i m i n e d a l t e r t h e i n i t i a l s t a h i l i z a t i o n of i n t i a o e u l a i p r e s s u r e . S e e K i n s . I , 2 , a n d 3 f o r t h e t i m e s of d e t e r m i n a t i o n of C , , , , .
" S i x d e t e r m i n a t i o n s of t o t a l o i i t l l o w l a c i l i t v w e r e m a d e , ' p > 0 . 0 0 1 ; - 0 . 0 0 5 ... p .;• 0 . 0 0 1 ; H').O25 > p 0 . 0 1 ; ' 0 . 0 5 > p
,> 0 . 0 2 5 ; ''(I.I > p > 0 . 0 5 ; " N o t s i ^ n i K c i i n t l v d i l f e r e n t . T h e t o t a l o i i t l l o w f a e i l i t \ a t v a r i o u s t i m e s is c o m p a r e d w i t h t h e
i n i t i a l p r e - d r u y v a l u e f o r t h a t p r o s t a y l a n d i n r o u t e , a n d t i m e N = N u i n h e r of d e t e r m i n a t i o n s .
Materials and methods.
Solutions employed. Ten milligrams ol PCE, 01
I'CLV;
wcic
dissolved
i n 1 n i l . <>l u t h a i i o l . T w o
hundred inieioliters ol this solution was diluted
with 1.8 ml. ol sodium carbonate solution (0.2 nig.
per millilitcr). This solution was divided into 20
tubes each containing 0.1 ml. and the solutions
dozen. For intravenous injections, one tube was
taken and 0.9 ml. of 0.9 per cent i\aCI solution
was added, giving a solution containing 0.1 ing.
PC per inilliliter; a similar solution without PC
was used in the control infusion periods. For
topical applications, 0.4 ml. ol NaCI solution was
added to a lube containing PC and 50 fi\ ol this
solution (containing 10 /*g) was applied topically
to the eye. In some control eyes a similar solution
without PC was applied to the eye.
Proveduiv. Adult albino rabbits, two to three
kilograms, of either sex were anesthetized with
25 per cent methane in 0.9 per cent NaCI solution. Approximately 30 ml. gave a suitable depth
of anesthesia. A 22-gaugc needle connected to a
transducer, which also connected to a capillary
tube by way ol a T-coiiiiection, was inserted into
the anterior chamber by hand and the intiaocular
pressure recorded. If the intraocular pressure was
unstable or rising the eye was discarded: normally
the intraocular pressure was stable within two to
five minutes alter insertion of the needle. Total
oiitllow facility ( d . . , ) was determined in one
eye ol each pair using the method of Barany"1 using an increment of 5 mm. Ilg pressure. T h e other eye served either as a control
(topical application) or as a check that the intraocular pressure response was unalleeted by the
determination of facility (intravenous infusion).
The following experiments were pertormed: inlu-
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sion of prostaglandin vehicle for 30 minutes followed by 60 minute inlusion of 0.79 /ug per 7.9
/'I per minute I'CIL, OI PCE: or topical application
of 10 Mg PCE, or PCE... For both the 10 minute
infusion and topical application the only pre-drug
period was that time prior to stabilization of the
intraocular pressure. T h e intravenous inlusion ol
this quantity of PC elevates intraocular pressure
by 10 to 20 mm. Hg. Total outflow facility was
determined at 10, 30, and 60 minutes after initiation of the infusion or topical application, and for
the 10 minute intravenous infusion also at 90
minutes. II the intraocular pressure after any
determination of Cm, was not within 2 mm. I l g of
the pre-G\,,i pressure the eye was discarded.
Results. Inlusion of vehicle alone for 30 minutes
has no ellect on intraocular pressure ( F i g . 1) or
Ci.,1 (Table 1). T h e repeated determination ol
C,,,i in the same eye has no ellect on the course
of the intraocular pressure, as illustrated by the
pie- and post-facility pressures in all eyes ( Figs.
1, 2, and 3 ) . T h e pressures of the eyes in which
lacilitv was determined exactly parallel that in
the eyes in which no lacilitv determinations were
made; the mean pressure difference between
paired eyes during all infusion experiments is
0.4 mm, Ilg. Thus, neither the PC vehicle nor the
measurement of C,,,, had any ellect on intraocular
pressure.
With all three modes of administration of PC
there is a typical 10 to 15 mm. Hg intraocular
pressure rise in the first 10 minutes. The 60-ininute
inlusion causes an elevation of pressure over the
baseline lor about 45 to 50 minutes and therealter, despite continued infusion, the values fall
below the original intraocular pressure ( F i g . 1).
Alter the cessation of the 10-minute infusion the
38
O)>litlialii\ologij
ianunni 1975
Investi
Reports
0
5
10
15 20 2b 30
0
5
TIME
10 15 20 25
(mm)
30
35 40 45 50
55
60
Fig. 1. Ellect of prostaglandin vehicle and 60-mimite infusion of PCE, and PCE.. on intraocular
pressure. •
• , PCE,; O
O, PCE.; A
A, PCE, control; A
A, PCE. control.
Total outflow facility was determined where indicated by C. Values are the mean t S.E.M. ot
12 determinations.
40
15
w
10
E
1
a
25
2
20
15
10
15
20
25
30
35 40
TIME
45
50
(mm)
55
60
65
70
75
80
85
90
Fig. 2. Ellect of 10-miniite infusion of PCE, and PCE, on intraocular pressure. •
• , PCE,;
O
O, PCE... Total outflow facility was determined where indicated by C. Values are the:
mean t S.E.M. of 24 determinations for PCE, and 12 determinations for PCE:.
intraocular pressure tails rapidly below the original
intraocular pressure and remains at this level lor
up to 60 minutes (Fig. 2 ) . With topical application of 10 <ug of PCE, or PCE.. there is a substantial elevation of intraocular pressure which begins
to fall at a b o u t 3 0 to 4 0 m i n u t u s , but is still a b o v e
the original intraocular pressure at 60 minutes
(Fig. 3 ) . The control eve shows an initial consensual response to PC in the treated eve, which
is followed by a period where the intraocular pressure tails below baseline and is maintained at this
level.
The determinations of C,,,i show that the value
has not increased significantly over the control at
10 minutes alter the addition of either systemic
or topical PC. Indeed, the 10-iniiiute and pie-chug
Ci.,1 values arc very similar, despite the fact that
the intraocular pressure is almost at a maximum
alter 10 minutes. With intravenous infusion C,..i
has increased at 30 minutes only by a barely
significant amount. The C,,,, value at 30 minutes
following topical PC application, and at 00 and
90 minutes tor all routes of administration, is
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significantly increased over the pie-drug values
(Table I).'
Discussion. The intravenous infusion of PCE,
or PCE- lor 10 or 60 minutes induces an elevation
of intraocular pressure, as found previously, 1 as
does the topical application ol 10 Mg of PCE, or
PCE-...-- •' Since C m is unchanged during a period
when the intraocular pressure reaches a peak an
explanation must be sought for the increase in
intraocular pressure under these conditions.
We have shown that aqueous inllow can be expressed as'1:
L,,A [x, ( P , - P o ) - Pi] + S
where L,, is the permeability of the ciliary epithelium, A is the area, x, is the "pressure index," 7 P.
is capillary pressure, P,, is plasma colloid oncotic
pressure, Pi is intraocular pressure, and S is secretion. P,, has been experimentally determined as
21 mm. Hg, s and under the conditions of the
experiments reported here is constant.
In order to cause an elevation in intraocular
pressure during the initial phase of PC eflects in
Reports
Volume 1<1
Number 1
39
35 -
E
E 25
H 20 -
T
C i
I C
10
i
i
15
20
,C
25
50
TIME
(mm)
i
55
T
T
*
1
1
10
45
i
1
50
55
T
C |
60
Fig. 3. Efleet of topical application of 10 jug of PGE, and PGE; on intraocular pressure.
•
• , PGE,; O
O, PCE.; A
A, PCE,"control; A
A, PCE, control. Total outflow
facility was determined where indicated by C. Values are the mean i S.E.M. of 6 determinations.
the absence of any change in Cn.i, none of the
parameters L,,, A, or x,, must change, since
L,,Ax, = CI.,I."
There could, of course, be compensatory changes
in each parameter which would be ollsetting and
not upset the equality in the equation. It is known,
however, that L,, is increased by PC. after 20
minutes exposure'1 and so is x., as evaluated by
the increased perfusion of the ocular vessels 30
minutes alter PC.1" The other parameter, A,
would, in face of increased vascular perfusion, also
be expected to increase since the perfusion area
would be enlarged. It is difficult to visualize that
changes in these parameters before 30 minutes
would be qualitatively different from the later
responses, and thus one concludes that none of
the parameters change at early times alter initiation of PC treatment.
The doses of PC required to stimulate secretion,
S, in vitro are well above those reported as causing
ocular hypertension in vivo,'1 and it has been
suggested" that the in vivo action may be ^^ to
increased permeability of the blood-aqueous barrier
rather than the stimulation of epithelial transport.
Measurements of the permeability of the isolated
ciliary epithelium after treatment with PC suggest
that pseudofacility, or CMs, would be increased, in
a dose-dependent manner, about 20 minutes after
a specific drug concentration bathed the tissue.'1
Evidence has also been obtained in the whole
animal to indicate that C,,s is increased and Citu,is unchanged following topical PC1-' :| but these
measurements were also made 30 minutes after
drug application.
Intraocular pressure, Pi, is increased almost immediately after PC administration and with no
change in any other parameter of the equation
this would logically necessitate that there be a
decrease in aqueous humor formation, if all the
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parameters remained constant, and there is no
evidence that any parameter should change except
P,. Aqueous humor formation (aqueous inllow)
is increased after PC application, however, and is
responsible for the elevation in Pi and an increase
in P,, or capillary pressure, would be responsible
for this increase.
It has been shown that topical PC causes a
mailed vasodilation, particularly at the base of the
iris, concurrent with an increased vascular permeability when measured 30 minutes after PC application.10 The increased vascular permeability ol
the iris vessels changes the characteristics of the
iris capillaries from a system where very little
lluorescein emerges into the anterior chamber to a
very leaky system capable of filling the anterior
chamber with dye in less than 10 minutes.1"
It would seem, therefore, that the initial intraocular pressure rise seen after intravenous or
topical PC is caused by the vasodilatory effects of
the drug. Vasodilation would cause a change
primarily in capillary pressure and hence vascular
permeability due to an increase in vessel diameter.
The increase in P, would force more fluid out of
the capillaries thereby increasing ultrafiltration.
These ellects would be more pronounced if the
vasodilation was primarily on the afferent ciliary
blood vessels, and, in view of the marked ellect
of PC's on intraocular pressure it is most probable
that the initial effect would be confined to these
vessels. Masuda and Mishima11 have, indeed, found
that the mean capillary pressure is increased when
measured 30 minutes after topical PC treatment
even during maintenance of constant systemic
blood pressure.
The initial phase of PC-induced ocular hypertension, therefore, is caused by vascular changes,10
namely an increase in vascular permeability and
vessel vasodilation. This phase is followed, as the
PC concentration is locally elevated in the eye,
40
hwustigtititjc Ophthalmology
January 1975
Reports
by siii increase in the permeability of the ciliary
(.•pithelium us well us possible changes in iris
vascular permeability. These changes thereby result in an increase in the measured total outflow
facility clue to the increase in Cp- alone, since
C,,v is a measure of the permeability of the ciliary
epithelium.'1 All the changes caused by PC, therefore, appear to be restricted to the aqueous inflow
rather than having any involvement with
trabecular, or true, outflow facility.
From the Departments of Ophthalmology and
Physiology, Medical College of Georgia, Augusta,
Ca. 30902. This study was supported in part by
United States Public Health Service Research
Grant EY 00863 from the National Eye Institute.
Submitted for publication Aug. 5, 1974. Reprint
requests: K. Green, Ph.D., Room 3 D 11, R & E
Building, Medical College of Georgia, Augusta,
Ga. 30902. We thank Mrs. Debbie Graves for her
assistance in the preparation of this manuscript.
The prostaglandins were generously provided by
Dr. |. E. Pike, The Upjohn Company, Kalamazoo,
Mich.
Key words: prostaglandins, rabbit, intraocular pressure, total outflow facility, aqueous formation,
vasodilation, capillary pressure.
REFERENCES
1. Waitzman, M. B., and King, C. D.: Prostaglandin influences on intraocular pressure and
pupil size, Am. |. Physiol. 212: 329, 1967.
2. Kass, M. A., Podos.S. M., Moses, R. A., et
al.: Prostaglandin E, and aqueous humor
dynamics,
INVEST. OPHTHALMOL,
II:
1022,
1972.
3. Masuda, K., and Mishima, S.: Effects of
prostaglandins on inflow and outflow of the
aqueous humor in rabbits, Jap. J. Ophthalmol.
17: 300, 1973.
4. Chiang, T. S., and Thomas, R. P.: Ocular
hypertension following intravenous infusion
of prostaglandin E,, Arch. Ophthalmol. 88:
4 18, 1972".
5. Barany, E. H.: Simultaneous measurement of
changing intraocular pressure and outflow
lacility in the vervet monkey by constant
pressure infusion,
INVEST. OPHTHALMOL.
3:
135, 1964.
6. Pederson, J. E., and Green, K.: Aqueous
humor dynamics: A mathematical approach to
measurement of facility, pseudofacility, capillary pressure, active secretion, and x,., Exp.
Eye Res. 15: 265, 1973.
7. Barany, E. H.: A mathematical formulation
of intraocular pressure as dependent on secretion, ultiafiltration, bulk outflow, and osmotic
reabsorption of fluid, INVEST.
OPHTHALMOL.
2: 584, 1963.
8. Pederson, J. E., and Green, K.: Aqueous
humor dynamics: Experimental studies, Exp.
Eye Res. 15: 277, 1973.
9. Green, K.: Permeability properties of the
Downloaded From: http://iovs.arvojournals.org/ on 06/14/2017
ciliary epithelium in response to prostaglandins,
INVEST. OPHTHALMOL.
12: 752, 1973.
10. Whitelocke, R. A. F., and Eakins, K. E.:
Vascular changes in the anterior uvea of the
rabbit produced by prostaglandins, Arch.
Ophthalmol. 89: 495, 1973.
Adenosine 3',5'-monophosphate increases
the outflow of aqueous humor from the
rabbit eye. ARTHUR H. NEUFELD, DAVID
K. DlJEKER, TORGEIR VECCE, AND MARVIN
L. SEARS.
Direct administration of cyclic-AMP into the.
anterior chamber increases the outflow facility of
the eye for aqueous humor. This is consistent with
the hypothesis that catecholamines lower the
intraocular pressure of the rabbit eye, at least in
part, by a cyclic-AM P-mediated mechanism. This
mechanism is active in the outflow channel? and
increases the rate at which aqueous humor leaves
the anterior chamber.
Adrenergic agonists, administered to the eye,
decrease intraocular pressure. The mechanism ol
this response is important because catecholamines
may have a role in the physiologic regulation of
intraocular pressme and because the clinical use ol
topical epinephrine is an ellective therapy for
primary open-angle glaucoma. One of the means
by which a decrease in intraocular pressure occurs
is an increase in the outllow of aqueous humor.
In the rabbit eye, the outflow of aqueous humor
responds to catecholamine stimulation1; however,
the site of action and the mechanism by which
adrenergic agonists influence outflow are unknown.
We wish to report what we believe is the next
step in a series of events that leads to increased
outflow of aqueous humor after an endogenous or
exogenous adrenergic stimulus. We have demonstrated that adenosine 3',5'-monophosphate (cyclic-AMP), administered directly into the anterior chamber of the rabbit eye, increases the outflow facility of the eye for aqueous humor.
Methods. Two to three kilogram male albino
rabbits were anesthetized with intravenous
urethane (25 per cent w/v) and given aspirin
(600 mg.) rectally. As a control, three animals
were not pretreatecl with aspirin. The anterior
chamber of one eye was cannulated with two
needles using the needle gun.1-' One cannula was
used for delivery of the drug; the other cannula
was connected by saline-filled polyethylene tubing
to a transducer and a reservoir and was used to
monitor intraocular pressure and to allow perfusion
of the eye. Outflow facility was measured by perfusion at two levels of constant pressure, usually
P, = 25 and P, = 30 mm. Ilg. The How from