Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0595921 (intraocular pressure)
 11,750 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of timolol, propranolol, epinephrine, and isoproterenol on intraocular pressure (IOP) (measured by tonometry) were compared after topical administration in conscious rabbits. Epinephrine and isoproterenol decreased IOP in normotensive rabbits, whereas propranolol had no effect. Timolol produced only a slight and inconsistent lowering of IOP in normotensive rabbits. All four agents reduced IOP elevated by an oral water load; the adrenergic agonists were substantially more active than the two beta-adrenergic blocking agents. In alpha-chymotrypsin-induced ocular hypertension, epinephrine, isoproterenol, and timolol were essentially equally effective, whereas propranolol exhibited only weak activity. In this latter model, timolol did not lose its effectiveness after multiple instillations (three/day) over an 8-day period. The concentration of timolol in the acqueous humor after topical application of effective hypotensive doses was relatively high as compared to that found in plasma. In addition, topical doses of timolol required to lower IOP were considerably greater than those needed to reduce or block the ocular hypotensive activity of isoproterenol. The mode of action and therapeutic implications of beta-adrenergic blocking agents in glaucoma are discussed.
 ...
PMID:Comparison of the effects of timolol and other adrenergic agents on intraocular pressure in the rabbit. 2 Nov 45

The ocular hypotensive efficacy of continuously delivered epinephrine is compared to that of pulsed doses provided by eyedrops in both normotensive and hypertensive rabbit eyes. In normotensive eyes, 2 microgram/hr and 4 microgram/hr epinephrine delivered into the tear film continuously for 12 hours reduces intraocular pressure as well as eyedrop pulses of 0.5% epinephrine hydrochloride or 2% epinephrine bitartrate (doses of 500 and 1100 microgram, respectively). Ocular hypertension induced by an intragastric water load in rabbits is significantly inhibited by continuous delivery of epinephrine at the rates of 3 or 6 microgram/hr, or by 2% epinephrine bitartrate (1% free base) eyedrops. Epinephrine delivered continuously at rates of 2-6 microgram/hr for 6 to 12 hours (12-72 microgram total) has hypotensive efficacy equivalent to 15 to 40 times as much epinephrine applied once in eyedrops. Epinephrine bitartrate eyedrops reduce tear film pH well below normal. Continuous delivery of epinephrine bitartrate does not reduce tear film pH below normal levels.
 ...
PMID:Ocular hypotensive efficacy of topical epinephrine in normotensive and hypertensive rabbits: continuous drug delivery vs eyedrops. 2 54

The uveal absorption of aqueous humor at two different intraocular pressures was measured in rhesus monkeys by sampling vortex vein blood during anterior chamber perfusion of Ringer's solution containing both fluorescein and 125I albumin. At 20 mm. Hg, an excess of fluorescein equivalent in amount to 0.45 microliter/min. of anterior chamber perfusate and an excess of 125I albumin equivalent to 0.18 microliter/min. of perfusate was found in the vortex vein blood compared to systemic blood. At 32 mm. Hg, an excess of 0.86 microliter/min. of fluorescein and 0.26 microliter/min. of 125I albumin was measured. The increase in fluorescein absorption at the higher intraocular pressure was significant (0.025 less than p less than 0.05), with a uveal outflow facility of 0.034 microliter/min./mm. Hg. At an intraocular pressure of 20 mm. Hg, uveal aqueous outflow is less than 10% of total aqueous outflow. The pressure dependence of the uveal uptake of fluorescein implies an aqueous reabsorption into the uveal vessels by ultrafiltration. Uveoscleral aqueous "outflow" appears to consist of intraocular uveal reabsorption of water and small molecules from the aqueous, with only larger molecules like albumin actually leaving the eye through posterior scleral vessel perforations. This reabsorption plays a minor role in intraocular pressure regulation under normal conditions.
 ...
PMID:Uveoscleral aqueous outflow in the rhesus monkey: importance of uveal reabsorption. 41 Jul 50

The ocular effects in rabbits of topically applied labetalol hydrochloride, a new alpha- and beta-adrenergic receptor blocking agent, were studied. A dose-related reduction in intraocular pressure (IOP) followed treatment with 0.01% to 1% solutions. Labetalol at a 1% concentration had no effect on pupil diameter. The same dose blocked an increase in IOP after water loading but did not significantly alter the coefficient of aqueous outflow facility. Mydriasis induced by phenylephrine hydrochloride was competitively inhibited.
 ...
PMID:Ocular effects in normal rabbits of topically applied labetalol: a combined alpha- and beta-adrenergic antagonist. 42 92

Our ability to induce glaucoma in birds provides an experimental system for exploring the mechanisms involved in the provocative water test. Waters loads of a level comparable to those used clinically produced larger intraocular pressure (IOP) changes in preglaucomatous and glaucomatous birds than in control birds. The magnitude of the response corresponded to the level of IOP before testing, that is, to the severity of the glaucoma. Changes in systemic blood pressure were not involved in the response. While hyotonicity of plasma may be the systemic determinant, the normal range of variation in this factor does not allow us at present to consider this a causal relationship.
 ...
PMID:The water provocative test in preglaucomatous chickens. 48 54

The possibility that fibers regulating the intraocular pressure originate in the hypothalamus and course in the optic nerve, has been investigated in albino rabbits with different techniques. By means of horseradish perixodase tracing-technique, oculohypothalamic but no hypothalamoocular connections were observed. The water-loading effect on the intraocular pressure was studied after unilateral optic nerve transection. The transection was performed in three experimental groups in the following way: Intracranial transection of one optic nerve, retrobulbar transection of one optic nerve and sham operation on the other side, retrobulbar transection of one optic nerve without sham operation on the other side. In contrast to previous reports, we found no significant side difference in intraocular pressure after water-loading in any of these groups.
 ...
PMID:A study on the postulated transoptic regulation of the intraocular pressure. 58 Aug 41

Intraocular pressure response to systemically administered osmotic agents was studied in albino rabbits with one optic nerve transected and the fellow optic nerve left intact. There eas a significant increase in intraocular pressure of both eyes following water ingestion but no significant difference in the pressure rise of the two eyes. There was a significant decrease in intraocular pressure of both eyes following glycerol ingestion but no significant difference in the pressure fall of two eyes. These results do not support the hypothesis that the optic nerve carries fibers which are part of the control system for intraocular pressure.
 ...
PMID:Intraocular pressure after optic nerve transection. 62 Nov 30

A new gonio-cycloscope that magnifies an object up to 1.5 times was designed to observe the ciliary process and chamber angle. As a result of aging, the ciliary process became hypertrophic and more branched with discoloration. Leakage of fluorescein from the ciliary process decreased as intraocular pressure artifically increased, stopping completely at 50 mm Hg or more. Water drinking accelerated fluorescein leakage, while oral glycerol diminished it.
 ...
PMID:Cycloscopy and fluorescein cycloscopy of the ciliary process. 91 Aug 52

Heavily pigmented eyes have been shown to be relatively resistant to pilocarpine, and present special problems in management of open-angle glaucoma. Studies have suggested that the hypotensive effect of pilocarpine may be influenced by the vehicle; therefore, 13 relatively resistant black patients (26 eyes) were selected for a clinical comparison of pilocarpine as delivered in two different polymer vehicles. One vehicle was composed of 1.67% polyvinylpyrrolidone and BP water-soluble polymers (Adsorbobase); the other of hydroxypropyl methylcellulose 0.5%. All patients had been under treatment with the pilocarpine/methylcellulose preparation; 20 of the 26 eyes were judged to be uncontrolled (IOP above 21 mm Hg). Control of intraocular pressure was promptly obtained with the pilocarpine/Adsorbobase solution, and maintained at lower pilocarpine concentrations than with the previous therapy. Often, frequency of instillation could be decreased. This clinical comparison suggests that the Adsorbobase vehicle appreciably enhances corneal penetration and availability of pilocarpine. Three cases are discussed demonstrating the need for titration when instituting a new therapy with as little as one fourth the concentration of the previous pilocarpine therapy.
 ...
PMID:Clinical comparison of pilocarpine preparations in heavily pigmented eyes: an evaluation of the influence of polymer vehicles on corneal penetration, drug availability, and duration of hypotensive activity. 92 Nov 44

Four animals received unilateral optic nerve sections which ablated that eye's rise in intraocular pressure in response to water drinking. Bilateral supraoptic nucleus lesions in two animals resulted in ablation of the other eye's response to water drinking. Both animals showed histopathologic proof of the lesion site. Two animals received sham operations for the supraoptic nucleus lesions with no change in their differential response to water drinking. This report gives preliminary evidence of the hypothesis of a supraoptic nuclear control mechanism of intraocular pressure.
 ...
PMID:A preliminary report on the supraoptic nucleus and control of intraocular pressure. 111 Jan 32


1 2 3 4 5 6 7 8 9 10 Next >>