Biomedical subjects

Kimiya Shimizu

Publications and source records attributed to Kimiya Shimizu.

At least 19 recordsLinked to original sources

PubMed2007

Expression and cellular localization of melatonin-synthesizing enzymes in the rat lens.

Melatonin (N-acetyl-5-methoxytryptamine) prevents oxidative stress-induced cataract development, and previous studies have suggested that the ocular lens synthesizes melatonin. In the present study, we examined whether two key enzymes in melatonin biosynthesis, arylalkylamine N-acetyltransferase (AANAT) and hydroxyindole-O-methyltransferase (HIOMT), are expressed in the lens of adult male rats. Reverse transcriptase-polymerase chain reaction analyses demonstrated that both AANAT and HIOMT mRNAs are expressed in the lens. Western blotting for AANAT protein showed that the lens, like the pineal gland, contains this enzyme protein with a molecular mass of 24 kDa. Immunohistochemistry revealed that AANAT protein is localized to the lens cortical fiber cells. Serotonin, which is a substrate for AANAT and a melatonin precursor, was also found in this region. These findings demonstrate that the lens expresses AANAT and HIOMT, and suggest that the cortical fiber cells are the main melatonin-synthesizing sites in the lens. Locally synthesized melatonin in the lens cortical fiber cells may protect the lens itself from cataract development.

Acetylserotonin O-Methyltransferase↗

PubMed2006

Effect and mechanism of betaxolol and timolol on vascular relaxation in isolated rabbit ciliary artery.

PURPOSE: In order to clarify the vasodilatory mechanism of betaxolol and timolol, we studied the effects of these drugs in isolated rabbit ciliary arteries. METHODS: Rabbit ciliary artery specimens were mounted in a double myograph system, and betaxolol, timolol, or another agent was introduced into the organ chamber. The mechanical response of the arteries was studied using an isometric tension recording method. The intracellular free calcium concentration [Ca2+]i was also measured using fluorescence photometry. RESULTS: Betaxolol and timolol induced dose-dependent relaxation in the rabbit ciliary arteries precontracted by high-K+ Krebs solution. The minimum concentrations required to cause relaxation were 10 microM of betaxolol, and 30 microM of timolol. At the maximum concentration of 1 mM, betaxolol induced almost complete relaxation of the ciliary arteries, whereas timolol induced approximately 70% relaxation. These actions were not inhibited by pretreatment with 100 microM NG-nitro-l-arginine methylester (L-NAME), a nitric oxide synthase inhibitor, or by denudation of the vascular endothelium. However, 300 microM of betaxolol or timolol decreased the [Ca2+]i of the vascular smooth muscle, an action similar to that of diltiazem, a typical L-type voltage calcium-channel blocker. CONCLUSIONS: Betaxolol, a selective beta1-adrenoceptor antagonist, and timolol, a nonselective beta-adrenoceptor antagonist, both frequently used in the medical management of glaucoma, decrease [Ca2+]i by acting as Ca2+ channel blockers, thus causing relaxation of isolated rabbit ciliary artery.

Adrenergic beta-Antagonists↗

PubMed2006

Pharmacological vascular reactivity in isolated diabetic rabbit ciliary artery.

Impairment of the ocular circulation induced by diabetes mellitus has not been fully defined, but is thought to be related to hemodynamic changes in the ocular circulation. The purpose of the present study is to investigate the functional and morphological changes occurring in the ciliary artery wall of rabbits with alloxan-induced diabetes mellitus. A single intravenous bolus injection of alloxan (100 mg/kg) was given to each of 26 10-week-old rabbits and 16 sham-injected control rabbits. Twenty weeks later, control rabbits and diabetic rabbits were sacrificed, and their ciliary arteries were mounted in a myograph system. The responses of these arteries to high K+ solution (K-Krebs solution), phenylephrine and carbachol were investigated using isometric tension recording. L-NAME (NG-nitro-l-arginine methyl ester; 100 microM) and indomethacin (1 microM) were also used to test the mechanism causing the carbachol induced relaxation. The arteries were also examined morphologically. The maximum tensions induced by K-Krebs solution in this tissue were not significantly different: 17.2+/-0.8 mN (n=16) in the control rabbits and 17.6+/-0.8 mN (n=23) in the diabetic rabbits (P=0.36). Phenylephrine caused dose-dependent contraction with EC50 values of 1.3+/-0.4 microM (n=6) in the control and 5.1+/-2.3 microM (n=6) in the diabetic rabbits, but there was no significant difference between the two (P=0.36). Carbachol induced dose-dependent relaxations in segments precontracted with K-Krebs solution. These relaxations were significantly reduced in the diabetic rabbits. The maximum relaxation induced by carbachol was 77.0+/-2.4% (10 microM) and 66.4+/-2.5% (100 microM) in the control and diabetic rabbits, respectively. These values were significantly different (P=0.0076). The IC(50) value for carbachol was 396.3+/-58.4 nM (n=16) in the control, and 443.6+/-141.1 nM (n=23) in the diabetic rabbit (P=0.87). Application of a 100 microM nitric oxide synthase inhibitor, L-NAME, significantly inhibited the amplitude of relaxations evoked by carbachol (P=0.0066). However, these relaxations were not inhibited by pretreatment with 1 microM indomethacin (P=0.60). Histologically, the frequency of invaginations was less in the diabetic arterioles with a flattening of the lamina in the diabetic rabbits than in the controls. The cytoplasm of endothelial cells contained large vacuoles, indicating weak adhesion to the lamina. Some endothelial cells even showed vacuolar degeneration due to breakdown of the cell membranes. However, the smooth muscle cells were well preserved in the diabetic rabbit. These results suggest that the mechanism of impairment of ocular circulation induced by diabetes mellitus is mainly the reduction of NO synthase due to endothelial cell dysfunction. Furthermore, the characteristics of rabbits with alloxan-induced diabetes mellitus probably make them a useful model for investigating ocular complications induced by diabetic mellitus.

Animals↗

PubMed2006

Changes in the crystalline lens resulting from insertion of a phakic IOL (ICL) into the porcine eye.

BACKGROUND: Insertion of a phakic IOL offers these advantages: the corneal optical zone is not dissected or resected; preservation of the crystalline lens results in preservation of the accommodation force; and since the phakic IOL is removable, any error or change in refraction can be countered by exchanging it. However, the cause of secondary cataracts has never been clarified or discussed to date. METHODS: The following ICL lenses were inserted under general anaesthesia into 20 eyes of ten 3-month-old miniature pigs: a minus lens without holes into five eyes, a plus lens in two eyes, a minus lens with four holes around the lens haptics in three eyes, and a minus lens with a central hole in the optic in three eyes; and seven eyes were used as controls. The anterior segments were then photographed 1 week, 1 month and 3 months after surgery. At 3 months after surgery, Evans blue (EB) was infused into the vitreous under general anaesthesia, and after 30 min, the eyeball was enucleated, fixed and examined. RESULTS: In the case of the ICL without holes, the anterior subcapsular opacities were observed in all the eyes, and the anterior surfaces of the crystalline lenses were not stained with EB. Use of the ICL with four holes around the lens haptics resulted in light staining of the anterior surface of the crystalline lens, but the anterior subcapsular opacities observed were mild. As for the ICL with a hole in the centre of the optic, the anterior surface of the crystalline lens was stained and no anterior subcapsular opacities were observed. CONCLUSION: The results suggested that the insertion of an ICL brings about a change in the dynamics of the intraocular aqueous humour, reducing its circulation to the anterior surface of the crystalline lens. This is considered to cause a metabolic disturbance of the crystalline lens, resulting in anterior subcapsular opacification.

Animals↗

PubMed2006

Quantitative measurement of ocular dominance using binocular rivalry induced by retinometers.

PURPOSE: To develop a new method using binocular rivalry and retinometers to quantitatively examine ocular dominance and to investigate the magnitude of ocular dominance in cataract patients preoperatively and postoperatively. SETTING: Eye Clinic, Kitasato University School of Medicine Hospital, Sagamihara, Kanagawa, Japan. METHODS: The duration of exclusive visibility of the dominant and nondominant eye target in binocular rivalry were measured in 60 healthy volunteers (study 1) and preoperatively and postoperatively in 10 cataract patients (study 2). Rivalry targets were presented directly to the retina of each eye using 2 retinometers. Subjects reported the exclusive visibility of 1 eye target, and the total duration of exclusive visibility for each eye in dominant and nondominant eye trials was evaluated. RESULTS: In study 1, the magnitude of ocular dominance was quantitatively assessed with 4 grades based on differences in total duration of exclusive visibility between dominant and nondominant eyes. In study 2, magnitude of ocular dominance could be evaluated in all cataract patients regardless of refractive and cataract conditions. Magnitude of ocular dominance displayed significant correlations between preoperative and postoperative conditions (simple regression, P<.001). CONCLUSIONS: Ocular dominance can be quantitatively evaluated using this new method based on binocular rivalry and retinometers, particularly in cataract patients. Magnitude of ocular dominance may indicate preoperatively whether a patient with cataracts will have sufficient ocular dominance to adjust to monovision correction.

Adult↗

PubMed2005

Optical frequency-domain reflectometry with a rapid wavelength-scanning superstructure-grating distributed Bragg reflector laser.

Superstructure-grating distributed Bragg reflector lasers are particularly suited for optical frequency-domain reflectometry optical-coherence tomography with wide wavelength tunability and frequency agility. We report theoretical estimates of and experimental results for the data acquisition speed, the observable depth range, the resolution, and the dynamic range of an optical frequency-domain reflectometry system that uses a superstructure-grating distributed Bragg reflector laser whose wavelength can be tuned from 1533 to 1574 nm with a tuning speed of 10 micros/0.1-nm step.

Equipment Design↗

PubMed2005

Effects of ocular dominance on binocular summation after monocular reading adds.

PURPOSE: To investigate the relationship between ocular dominance and binocular summation with monocular reading adds. SETTING: Department of Orthoptics and Visual Science, School of Allied Health Sciences, Kitasato University, Sagamihara, Kanagawa, Japan. METHODS: Contrast sensitivities were measured by having subjects view contrast charts at spatial frequencies of 1.5, 3.0, 6.0, 12.0, and 18.0 cycles per degree after the addition of positive spherical lenses that ranged from +1.0 to +3.0 diopters (D). Through the use of a balance technique, the test group was quantitatively divided into 12 weak and 8 strong ocular dominance subjects on the basis of binocular rivalry. In study 1, binocular contrast sensitivity was measured in the weak and strong ocular dominances by adding a positive spherical lens in front of 1 eye, whereas the other eye was fixed at a corrected distance. RESULTS: In study 1, the binocular summation was observed only after adding positive spherical lenses in the nondominant eye. The differences in binocular contrast sensitivity that occurred after adding a positive spherical lens in the dominant eye versus that seen in the nondominant eye were statistically significant in the strong ocular dominance subjects who had +1.5 D and +2.0 D defocuses (P<.05; analysis of variance). CONCLUSIONS: Binocular summation was effectively maintained with reading adds in the nondominant eye and was significantly influenced by the magnitude of ocular dominance. Evaluating binocular summation after monocular reading adds seems to be a good method to evaluate adaptability to monovision.

Adult↗

PubMed2005

Intraocular pressure lowering effect of brinzolamide 1.0% as adjunctive therapy to latanoprost 0.005% in patients with open angle glaucoma or ocular hypertension: an uncontrolled, open-label study.

PURPOSE: A prospective study was conducted to evaluate the intraocular pressure (IOP) lowering effect of brinzolamide 1.0% ophthalmic suspension as an adjunctive therapy with latanoprost 0.005% ophthalmic solution in patients with open angle glaucoma or ocular hypertension. PATIENTS AND METHODS: Fourteen patients with open angle glaucoma (OAG) or ocular hypertension (OH) who had been using latanoprost 0.005% for more than 6 months were initiated on adjunctive brinzolamide therapy. The IOP values at 1 month, 2 months, and 3 months were compared with those measured immediately before adding brinzolamide to the regimen (baseline). The incidence of adverse events such as conjunctival hyperemia and corneal epithelial defect were also examined. RESULTS: The baseline IOP was 21.1 +/- 4.8 mmHg (mean +/- standard deviation). After 1 month, 2 months, and 3 months of therapy IOP was 16.9 +/- 4.5 mmHg, 16.6 +/- 4.0 mmHg, and 15.9 +/- 3.1 mmHg, respectively, showing significant reductions in IOP at all the measuring time-points during the study compared with the baseline value (p < 0.01). Conjunctival hyperemia developed in one patient after 1 month and in another after 2 months; however, both were mild, and therapy was continued. Corneal epithelium defect was observed in 3 patients. One of them had mild defect before brinzolamide was added to the regimen. Increase of eye discharge was seen in one patient. No serious side effects were otherwise observed. CONCLUSION: The addition of brinzolamide to a latanoprost 0.005% regimen may further lower intraocular pressure in patients with open angle glaucoma or ocular hypertension.

Aged↗

PubMed2005

[Long-term clinical course of laser in situ keratomileusis--two year follow-up].

PURPOSE: To evaluate the cases that were treated with laser in situ keratomileusis (LASIK) and who were follwed up for a full 2-year period without fail. MATERIALS AND METHODS: LASIK was performed in 62 eyes of 35 patients between June 1997 and March 1999. Mean age was 29.1 years and the preoperative mean spherical equivalent refraction was -6.90 +/- 2.49 (mean +/- standard deviation) diopter (D). Five aspects were studied as follows. RESULTS: 1. SAFETY: 26 eyes (41.9%) gained 1 line or more in best corrected visual acuity. Twenty eyes (32.3%) were unchanged. Sixteen eyes(25.8%) lost 1 line. No eye lost 2 lines or more. The safety index was 1.04. 2. EFFICACY: The efficacy index was 0.85. 3. Predictability: Forty-eight eyes (77.4%) were predictable within +/- 0.5 D, and 55 eyes (88.7%) were within +/- 1.0 D. 4. Stability: Manifest refraction was relatively stable after 3 months. 5. Complication: No complications were experienced. CONCLUSIONS: Our 2-year follow-up showed that postoperatively LASIK was safe and effective.

Adolescent↗

PubMed2004

Pharmacological vascular reactivity in isolated hypercholesterolemic rabbit ciliary artery.

We have investigated functional and morphological changes occurring in the wall of the hypercholesterolemic rabbit ciliary artery. A mutant rabbit with hypercholesterolemia and atherosclerosis was created by serial breeding. Ciliary arteries from hypercholesterolemic, age-matched control and young control rabbits' eyes were mounted in a myograph system. The effects of phenylephrine (PE), carbachol and electrical field stimulation on this artery were investigated using isometric tension recording methods. The arteries were also examined morphologically. PE caused dose-dependent contraction in young control, age-matched control and hypercholesterolemic rabbits. The EC(50) values were 1.0 microm (0.2-2.1, n = 6), 1.4 microm (0.4-2.4, n = 6) and 4.7 microm (1.8-7.7, n = 8) in the young, age-matched controls and in the Kurosawa and Kusanagi-hypercholesterolemic (KHC) rabbits, respectively. The EC(50) values of the KHC rabbit were significantly different from those of control. Electrical field stimulation evoked contraction only in the control rabbits. On the other hand, electrical field stimulation evoked relaxation when the ciliary artery was pre-contracted by 10 microm histamine in each type of rabbit equally. Carbachol also induced approximately equal dose-dependent relaxation after pre-contraction. The morphological findings of KHC rabbit ciliary artery revealed irregular contours on the internal elastic lamina and deformation of the shape of the medial smooth muscle cells with irregularity in size and widening of the intercellular spaces. However, the endothelial cells were well preserved. Compared with the ciliary artery, typical atherosclerotic changes existed in the intima, not the media, in the KHC rabbit aorta. In the hypercholesterolemic rabbit ciliary artery, the vasoconstricting function was reduced but vasodilatation was well preserved. Morphological findings supported this. The pharmacological vascular reactivity in the hypercholesterolemic rabbit ciliary artery is quite different from that of the large arteries.

Animals↗

PubMed2004

Ocular dominance and patient satisfaction after monovision induced by intraocular lens implantation.

PURPOSE: To elucidate the relationship between ocular dominance and patient satisfaction with monovision induced by intraocular lens implantation. SETTING: Eye Clinic, Kitasato University School of Medicine Hospital, Sagamihara, Kanagawa, Japan. METHODS: The durations of exclusive visibility of dominant- and nondominant-eye targets were measured in 16 patients with successful monovision and 4 patients with unsuccessful monovision to determine the characteristics of ocular dominance. The dominant eye was determined using the hole-in-card test (sighting dominance). The contrast of target in nondominant eye was fixed at 100%; the contrast of target in the dominant eye varied (ie, 100% to 80% to 60% to 40% to 20%) using rectangular gratings of 2 cycles per degree that were 4 degrees in size. RESULTS: In the successful monovision group, the reversal thresholds (ie, exclusive visibility of the nondominant eye crosses over that of the dominant eye) were displayed only at low decreasing contrast (80% and 60%). However, in the unsuccessful monovision group, the reversal thresholds were at high decreasing contrast (20%) or not at all. The reversal thresholds in patients with unsuccessful monovision were at a significantly lower contrast than in patients with successful monovision (P<.05). CONCLUSIONS: Success and patient satisfaction in monovision patients were significantly influenced by the magnitude of ocular dominance. The balance technique seems to be a good method to evaluate the quantity of ocular dominance and prospectively evaluate the monovision technique.

Adult↗

PubMed2004

Effects of dominant and nondominant eyes in binocular rivalry.

PURPOSE: To investigate the relation between sighting and sensory eye dominance and attempt to quantitatively examine eye dominance using a balance technique based on binocular rivalry. METHODS: The durations of exclusive visibility of the dominant and nondominant eye target in binocular rivalry were measured in 14 subjects. The dominant eye was determined by using the hole-in-card test (sighting dominance). In study 1, contrast of the target in one eye was fixed at 100% and contrast of the target in the other eye was varied from 100% to 80% to 60% to 40% to 20%, when using rectangular gratings of 1, 2, and 4 cycles per degree (cpd) at 2 degrees, 4 degrees , and 8 degrees in size. In study 2, contrast of the target in the nondominant eye was fixed at 100% and contrast of the target in the dominant eye was varied from 100% to 80% to 60% to 40% to 20%, when using a rectangular grating of 2 cpd at 4 degrees in size. RESULTS: In study 1, the total duration of exclusive visibilities of the dominant eye target; that is, the target seen by the eye that had sighting dominance was longer compared with that of the nondominant eye target. When using rectangular gratings of 4 cpd, mean total duration of exclusive visibility of the dominant eye target was statistically longer than that of the nondominant eye target (p < 0.05). In study 2, reversals (in which duration of exclusive visibility of the nondominant eye becomes longer than the dominant eye when the contrast of the dominant eye target is decreased) were observed for all contrasts except for 100%. CONCLUSIONS: The dominant sighting eye identified by the hole-in-card test coincided with the dominant eye as determined by binocular rivalry. The contrast at which reversal occurs indicates the balance point of dominance and seems to be a useful quantitative indicator of eye dominance to clinical applications.

Adult↗

PubMed2004

[The application of cross-linked hyaluronate hydrogel to trabeculectomy].

PURPOSE: We investigated the possibility of applying cross-linked hyaluronate hydrogel (HA gel) during trabeculectomy in rabbit eyes. SUBJECTS AND METHODS: 1. We injected 0.9% salt solution (n = 3), Opegan-HI (n = 3), or HA gel (n = 3) into the subconjunctiva to make a follicle, and investigated its size. 2. After making a limbal-based conjunctival flap and a scleral flap, we injected HA gel or 0.9% salt solution into the subconjunctiva of rabbit eyes and sutured each flap (n = 4 each). Three weeks after the operation, we incised the conjunctiva and investigated the case of peeling away the conjunctival flap or the scleral flap. 3. We performed trabeculectomy with and without subconjunctival HA gel (n = 7 and 6, respectively), and compared the reduction of intraocular pressure between the two groups. RESULTS: The results showed that the formation of the follicle was excellent and it was easy to peel away the adhesion. The reduction of intraocular pressure was statistically significant 4 weeks after the operation in which the HA gel was used. CONCLUSIONS: It could be useful to apply HA gel in trabeculectomy to prevent adhesion.

Animals↗

PubMed2003

Clinical outcomes of wavefront-guided laser in situ keratomileusis: 6-month follow-up.

PURPOSE: To evaluate the clinical outcomes 6 months after wavefront-guided laser in situ keratomileusis (LASIK) for myopia in Japan. SETTING: Department of Ophthalmology, Sanno Hospital, Tokyo, Japan. METHODS: This prospective study comprised 22 eyes of 12 patients treated with wavefront-guided LASIK who were available for evaluation at 6 months. The mean patient age was 31.2 years +/- 8.4 (SD) (range 23 to 50 years), and the mean preoperative spherical equivalent refraction was -7.30 +/- 2.72 diopters (D) (range -2.75 to -11.88 D). In all cases, preoperative wavefront analysis was performed with a Hartmann-Shack aberrometer and the Technolas 217z flying-spot excimer laser system (Bausch & Lomb) was used with 1.0 mm and 2.0 mm spot sizes and an active eye tracker with a 120 Hz tracking rate. The clinical outcomes of wavefront-guided LASIK were evaluated in terms of safety, efficacy, predictability, stability, complications, and preoperative and postoperative aberrations. RESULTS: At 6 months, 10 eyes had no change in best spectacle-correct visual acuity and 10 gained 1 or more lines. The safety index was 1.11 and the efficacy index, 0.82. Slight undercorrections were observed in highly myopic eyes. In all eyes, the postoperative refraction tended slightly toward myopia for 3 months and stabilized after that. No complication such as epithelial ingrowth, diffuse lamellar keratitis, or infection was observed. Comparison of the preoperative and postoperative aberrations showed that 2nd-order aberrations decreased and higher-order aberrations increased. In the 3rd order, aberrations increased in the high-myopia group (-6.0 D or worse) and decreased in the low to moderate-myopia group (better than -6.0 D). CONCLUSION: Wavefront-guided LASIK was a good option for refractive surgery, although a longer follow-up in a larger study is required.

Adult↗

PubMed2003

[Long-term clinical course of excimer laser photorefractive keratectomy].

PURPOSE: Long-term clinical follow-up for 5 years or longer has not yet been reported in Japan. We performed excimer laser photorefractive keratectomy(PRK) on 181 eyes from 1990 to 1993, and 44 of those eyes could be followed for 8 to 10 years. METHODS: The 44 eyes were divided into 3 groups depending on degree of correction. We compared of safety, efficacy, predictability-spherical equivalent, stability, complication, and satisfaction among the 3 groups. RESULTS AND CONCLUSIONS: The first generation PRK was certified clinically to be safe and stable in patients corrected for low to moderate myopia.

Adult↗

PubMed2003

[Late onset diffuse lamellar keratitis].

BACKGROUND: Diffuse lamellar keratitis (DLK) is marked by the presence of diffuse or multifocal infiltrates confined to the laser in situ keratomileusis(LASIK) interface. These infiltrates are culture-negative, and the etiology is thought to be noninfectious. Most cases of DLK occur within the first week or two following surgery. CASE: We describe two cases of diffuse lamellar keratitis that occurred 3 months after LASIK. These patients were treated with intensive topical corticosteroids. RESULTS: We treated the patients with topical corticosteroids, with rapid improvement in patient symptoms, visual acuity, and slit-lamp biomicroscopy. CONCLUSION: DLK may occur three months after LASIK.

Female↗

PubMed2003

[Transient dysfunction of the retinal ganglion cells after laser in situ keratomileusis].

PURPOSE: To evaluate the influence of high intraocular pressure(IOP) on the retinal ganglion cell function induced by suction during laser in situ keratomileusis(LASIK) using Frequency Doubling Technology(FDT). METHODS: Twenty-seven eyes of 15 patients were studied. Threshold values of 19 targeted areas, mean deviation(MD), and pattern standard deviation (PSD) were measured before LASIK, and 2 hours, 1 day, and 1 week after LASIK. These parameters obtained by N-30 program of FDT were compared between before and after LASIK. RESULTS: Significant decrease of MD and threshold value in all areas was recognized at 2 hours, but MD and threshold value in 6 of the 19 areas showed significant increase at 24 hours. Significant increase of PSD value at 2 hours was recognized. After 7 days, there were no significant differences in any parameters between before and after LASIK. CONCLUSION: These results indicated that a transient dysfunction of the magnocellular pathway might be induced by high IOP during LASIK procedure.

Adult↗

PubMed2002

Pharmacological effects of latanoprost, prostaglandin E2, and F2alpha on isolated rabbit ciliary artery.

BACKGROUND: Latanoprost is a prostaglandin (PG)F2alpha analogue widely recognized in the treatment of glaucoma. To investigate the action of this drug on the ocular circulation, we have studied its effects on isolated rabbit ciliary artery. The data obtained on this drug are compared with the data from PGE2 and PGF2alpha. METHODS: Under the microscope, ciliary artery specimens were prepared from rabbit eyes and mounted in a myograph system. The effects of latanoprost, PGE2, and PGF2alpha on the isolated rabbit ciliary artery were investigated in vitro using isometric tension recording methods. RESULTS: Exogenously applied PGF2alpha, but not latanoprost, evoked contraction in the rabbit ciliary artery. After precontraction with excess-[K]0 solution, latanoprost evoked relaxation dose-dependently. Latanoprost at a concentration of 100 microM induced maximum relaxation, which was not blocked by 10 microM L-nitro-L-arginine methylester (L-NAME), 1 microM 8-37 calcitonin gene-related peptide (CGRP) or 10 microM indomethacin. Moreover, latanoprost induced relaxation even in preparations without endothelium. The maximum relaxation obtained with PGE2 was somewhat less than 50% of that with latanoprost. CONCLUSIONS: These results indicate that latanoprost and PGE2 relaxed rabbit ciliary artery to different degrees. The relaxation provoked by latanoprost was not dependent on endothelium and was not caused by intrinsic PG, CGRP or nitric oxide. The mechanism of this relaxation is not yet clear.

Animals↗