Exp. Eye Res. (1978) 27, 687-690
The Effect of Carotid Artery Ligiation on Aqueous Humor Formation in the Rhesus Monlkey (Macaca mulatta) KARYK S. Ross, FRANK J. MACRI AND CARL KUPFER Clin~icul Bmnch, National
Eye Institute,
Mational
Institutes
of Health,
U.S. Department of Health, Education and Welfare, Bethesda,, Md 20014, U.S.A. (Received 5 April 19’78 mll in revised fom
27 Jwze 1978, London)
Ligation of one common carotid artery in the rhesus monke:y (Nacaca m.uZa.tta) resulted in an immediate decrease in aqueous humor formation rate in the ipsilateral eye. Over a period of four weeks, this affect became less marked. The findings of a decrease in aqueous humor formation indicates its dependence on plasma flow of the ciliary body. Key words : rhesus monkey; carotid artery ligation; aqueous humor formation; plasma flow; cilia.ry body.
1. Introduction It has been reported that acute common carotid artery ligation in rabbits may result in a decrease in the aqueous humor formation rate (Linn&, 1952). The purpose of this report is to examine the effect of acute and chronic unilateral common carotid artery ligation upon the aqueous humor formation rate in the rhesus monkey.
2. Materials and Methods Twelve male rhesus monkeys (MWGXU mulutta) uTeighing between 2.4 and 5.6 kg were sedated with an intramuscular injection of phencyclidine h.ydrochloride (0.5 mg/kg) and anesthetized with an intraperitoneal injection of urethan (500.0 mg/kg). The right common carotid artery was ligated, using two ligatures; a sha,m pro’cedure was performed on the left common carotid artery. Nine animals were allowed to recover from surgery at least three days before determination of aqueous humor flow rate. Each monkey underwent two to four identical analytical procedures at weekly intervals. Three animals were allowed a shorter recovery period of 2 hr before the same analytical procedures were performed. The anesthetized animals were held immobile in a supine position with a Picker FlexiCast sandbag. Aqueous humor formation rate was determined using a modification (Cevario and Macri, 1974) of a method previously described l(Macri, Dixon and Rall, 1965). Briefly, a 31 gauge stainless steel needle attached to a syringe microburet (Model SB2, Xcrometric Instrument Co.) with PE 10 tubing was inserted through the cornea of each eye at the limbus. The tip of the needle was advanceId until it was in the center of the anterior chamber. Fifteen min after placement of the needles, 10 ~1 of l25I radioiodinated/serum albumin (RISA) was injected into each eye. Two hours after the injection of RISA, the anterior chamber fluid of both eyes was completely aspirated to obtain the volume. In experiments 1 to 26, the aqueous humor was divided into two fractions for the R,eprint requests to: Dr Frank Macri, National Md 20014, U.S.A. 0014-483S/78/120687+04
Eye Institute,
$01.00/O
Building
10: Room 2D04, Bethesda,
0 1975 Academic Press Inc. (London) Limited 687
‘688
K.S.ROSS,V.J.MACRI
ASD C.KUPFER
determinations of: (1) aqueous humor turnover ments 27, 28 and 29 only the determination of Residual RISA was determined from duplicate a Nuclear Scintillation Counter. Kout (mill-1) previous publication (Macri et al., 1965) where: iTout inn-l
and (2) protein concentration. In experiaqueous humor turnover was performed. 25 ~1 samples of aqueous humor utilizing m-as calculated by methods similar t,o a
= In C,-In Ct Time
C,, = concentration of counts in anterior chamber at t,ime 0. C+,= concentrat,ion of counts remaining in anterior chamber at time t. Duplicate 10 ~1 samples of aqueous humor mere used for the determination of protein concentration (Lowry, Rosebrough, Farr and Randall, 1951). Protein concentrations greater than 175 mg y0 were considered abnormally high and the data discarded. The paired Student’s t-test was used for analyzing data. Results were considered significant if P < 0.05.
3. Resdts A total of 29 experiments were conducted with 12 monkeys. Data from one experiment was discarded because the aqueous humor protein concentration was abnormally high. A comparison of the mean results of t#he 28 experiments show that carotid artery ligation resulted in a significa,nt decrease in the calculated rate of aqueous humcr formation (gout min-r x anterior chamber volume) of 0.52 ,ul min-l (P < 0.002) TABLEI
Effect of carotid artery ligatiore on ctgz~eoecsi2ul~aoz,f~~~,lation at varying
2 Hours Monkey Rumber
PIOW
(pl min-I)
K out (min-I)
up to 2 weeks K out Flow (plmirl) (min-‘)
2 to 4 weeks Flow Kout (pl min-‘) (m&-l)
845
4.15
232 7s 350 253 384 887 894 685 688 337 352
5.96
Mean
4.91 3.74 0.0290 0.0220 3.08 2.58 0.0181 0.0148 3.53 0.54 0.44 0.0028 0.0017 0.29 0.23 0.0025 0.0017 0.22
iS.E.
P
4431
2.90 4.40 3.93
0.0273 0.0346 O-0252
0.0192 0.0250 0.0219 2.97 3.56 3.93 2.49 2.45
< 0.03
< 0.04
* () Eumber of determinations within the other time intervals.
inter.vn1.s
2.25 2.11 3.41 2.63 2.49
< 0.1
0.0151 0+?212 0.0264
0.0149 0.0125
0.0109 4.41(3)* 0.0138 %61(l) 0.0207 0.0154 0.0131
< 0.04
3.02(2) 3a(l) 2.80(l) 358(Q) 4.48(3) 3.45(3) ?A1(3)
3.57 3.07 2.50 4.06 2.72 3.79 3.41 2,57 3.63
0.0247 0.0159 0~0188 0.0216
0.0157 0.0248 0.022 0.0170 0.0200
0.0194 0.0183 0.0154 0.0262 0.0167 0.0247 0.0184 0.0129
0.0190
3.26 0.0201 0.0190 0.19 0.0012 0.0014
< 0.1
per animal within this time period. Only one determination
< 0.3
per animal
CAROTID
ARTERY
LIGATIOS
IN
PRIMATES
689
from a control of 3.73 ~1 nmr-1&O~19 to 3.21 roll min-l@13. hToUtwas reduced by 0.0028 (P < 0.004) from 0~0212f0~0011 to 0~0184f0~0009. The results of the 28 experiments were divided into three groups for further cornparisons (Table I) ; the division was made based on the time the experiments were performed after carotid artery ligation. The effect of ligation, two hours post surgery, significantly reduced the aqueous flow rate by 1-17 ~1 min? (P < O-03). For the time period of up to two weeks after ligation, the aqueous humor formation rate was reduced by 0.50 ~1 mm-1 (P < 0.01). Two to four weeka following ligation, it was reduced by only 0.27 ~1 min-r (P < 0.1). The effect of ligation on Eiout for t,he same time periods was a reduot.ion of 0.007 (P < 0.04), O-0033 (P
The Effect of Carotid Artery Ligiation on Aqueous Humor Formation in the Rhesus Monlkey (Macaca mulatta) KARYK S. Ross, FRANK J. MACRI AND CARL KUPFER Clin~icul Bmnch, National
Eye Institute,
Mational
Institutes
of Health,
U.S. Department of Health, Education and Welfare, Bethesda,, Md 20014, U.S.A. (Received 5 April 19’78 mll in revised fom
27 Jwze 1978, London)
Ligation of one common carotid artery in the rhesus monke:y (Nacaca m.uZa.tta) resulted in an immediate decrease in aqueous humor formation rate in the ipsilateral eye. Over a period of four weeks, this affect became less marked. The findings of a decrease in aqueous humor formation indicates its dependence on plasma flow of the ciliary body. Key words : rhesus monkey; carotid artery ligation; aqueous humor formation; plasma flow; cilia.ry body.
1. Introduction It has been reported that acute common carotid artery ligation in rabbits may result in a decrease in the aqueous humor formation rate (Linn&, 1952). The purpose of this report is to examine the effect of acute and chronic unilateral common carotid artery ligation upon the aqueous humor formation rate in the rhesus monkey.
2. Materials and Methods Twelve male rhesus monkeys (MWGXU mulutta) uTeighing between 2.4 and 5.6 kg were sedated with an intramuscular injection of phencyclidine h.ydrochloride (0.5 mg/kg) and anesthetized with an intraperitoneal injection of urethan (500.0 mg/kg). The right common carotid artery was ligated, using two ligatures; a sha,m pro’cedure was performed on the left common carotid artery. Nine animals were allowed to recover from surgery at least three days before determination of aqueous humor flow rate. Each monkey underwent two to four identical analytical procedures at weekly intervals. Three animals were allowed a shorter recovery period of 2 hr before the same analytical procedures were performed. The anesthetized animals were held immobile in a supine position with a Picker FlexiCast sandbag. Aqueous humor formation rate was determined using a modification (Cevario and Macri, 1974) of a method previously described l(Macri, Dixon and Rall, 1965). Briefly, a 31 gauge stainless steel needle attached to a syringe microburet (Model SB2, Xcrometric Instrument Co.) with PE 10 tubing was inserted through the cornea of each eye at the limbus. The tip of the needle was advanceId until it was in the center of the anterior chamber. Fifteen min after placement of the needles, 10 ~1 of l25I radioiodinated/serum albumin (RISA) was injected into each eye. Two hours after the injection of RISA, the anterior chamber fluid of both eyes was completely aspirated to obtain the volume. In experiments 1 to 26, the aqueous humor was divided into two fractions for the R,eprint requests to: Dr Frank Macri, National Md 20014, U.S.A. 0014-483S/78/120687+04
Eye Institute,
$01.00/O
Building
10: Room 2D04, Bethesda,
0 1975 Academic Press Inc. (London) Limited 687
‘688
K.S.ROSS,V.J.MACRI
ASD C.KUPFER
determinations of: (1) aqueous humor turnover ments 27, 28 and 29 only the determination of Residual RISA was determined from duplicate a Nuclear Scintillation Counter. Kout (mill-1) previous publication (Macri et al., 1965) where: iTout inn-l
and (2) protein concentration. In experiaqueous humor turnover was performed. 25 ~1 samples of aqueous humor utilizing m-as calculated by methods similar t,o a
= In C,-In Ct Time
C,, = concentration of counts in anterior chamber at t,ime 0. C+,= concentrat,ion of counts remaining in anterior chamber at time t. Duplicate 10 ~1 samples of aqueous humor mere used for the determination of protein concentration (Lowry, Rosebrough, Farr and Randall, 1951). Protein concentrations greater than 175 mg y0 were considered abnormally high and the data discarded. The paired Student’s t-test was used for analyzing data. Results were considered significant if P < 0.05.
3. Resdts A total of 29 experiments were conducted with 12 monkeys. Data from one experiment was discarded because the aqueous humor protein concentration was abnormally high. A comparison of the mean results of t#he 28 experiments show that carotid artery ligation resulted in a significa,nt decrease in the calculated rate of aqueous humcr formation (gout min-r x anterior chamber volume) of 0.52 ,ul min-l (P < 0.002) TABLEI
Effect of carotid artery ligatiore on ctgz~eoecsi2ul~aoz,f~~~,lation at varying
2 Hours Monkey Rumber
PIOW
(pl min-I)
K out (min-I)
up to 2 weeks K out Flow (plmirl) (min-‘)
2 to 4 weeks Flow Kout (pl min-‘) (m&-l)
845
4.15
232 7s 350 253 384 887 894 685 688 337 352
5.96
Mean
4.91 3.74 0.0290 0.0220 3.08 2.58 0.0181 0.0148 3.53 0.54 0.44 0.0028 0.0017 0.29 0.23 0.0025 0.0017 0.22
iS.E.
P
4431
2.90 4.40 3.93
0.0273 0.0346 O-0252
0.0192 0.0250 0.0219 2.97 3.56 3.93 2.49 2.45
< 0.03
< 0.04
* () Eumber of determinations within the other time intervals.
inter.vn1.s
2.25 2.11 3.41 2.63 2.49
< 0.1
0.0151 0+?212 0.0264
0.0149 0.0125
0.0109 4.41(3)* 0.0138 %61(l) 0.0207 0.0154 0.0131
< 0.04
3.02(2) 3a(l) 2.80(l) 358(Q) 4.48(3) 3.45(3) ?A1(3)
3.57 3.07 2.50 4.06 2.72 3.79 3.41 2,57 3.63
0.0247 0.0159 0~0188 0.0216
0.0157 0.0248 0.022 0.0170 0.0200
0.0194 0.0183 0.0154 0.0262 0.0167 0.0247 0.0184 0.0129
0.0190
3.26 0.0201 0.0190 0.19 0.0012 0.0014
< 0.1
per animal within this time period. Only one determination
< 0.3
per animal
CAROTID
ARTERY
LIGATIOS
IN
PRIMATES
689
from a control of 3.73 ~1 nmr-1&O~19 to 3.21 roll min-l@13. hToUtwas reduced by 0.0028 (P < 0.004) from 0~0212f0~0011 to 0~0184f0~0009. The results of the 28 experiments were divided into three groups for further cornparisons (Table I) ; the division was made based on the time the experiments were performed after carotid artery ligation. The effect of ligation, two hours post surgery, significantly reduced the aqueous flow rate by 1-17 ~1 min? (P < O-03). For the time period of up to two weeks after ligation, the aqueous humor formation rate was reduced by 0.50 ~1 mm-1 (P < 0.01). Two to four weeka following ligation, it was reduced by only 0.27 ~1 min-r (P < 0.1). The effect of ligation on Eiout for t,he same time periods was a reduot.ion of 0.007 (P < 0.04), O-0033 (P
