Prostaglandins involved in contractions by angiotensin II and bradykinin of isolated dog sphincter pupillae

Abstract

1 The dog isolated sphincter pupillae contracted in response to acetylcholine, angiotensin II

Effect of different dose schedules of travoprost on intraocular pressure and pupil size in the glaucomatous Beagle

“…The daily spikes in IOP may potentially cause more harm to the retinal ganglia cells and optic nerve head, 32 and ‘smoothing out’ these daily IOP fluctuations may also be beneficial in the dog. The canine isolated sphincter muscle appears sensitive to PGFα, which may act directly rather than through the release of adrenergic or cholinergic neurotransmitters 33,34 . The large decline in IOP as well as occurrence of miosis with the marked declines in IOP following twice‐daily instillations of 0.004% travoprost in the glaucomatous dogs suggests trabecular outflow as well as uveoscleral outflow may be increased.…”

The renin-angiotensin system in the human eye.

“…Angiotensin II contracts isolated dog sphincter pupillae via synthesis of cyclo-oxygenase products by acting on specific receptors. '5 33 The published data do not distinguish whether activated RAS in the eye is a cause or an effect of the investigated eye diseases. Logically, treatment with enzyme inhibitors, possessing sufficient lipid solubility to cross the blood ocular barriers, seems indicated in prophylaxis or therapy.…”

Effect of Different Dose Schedules of 0.15% Unoprostone Isopropyl on Intraocular Pressure and Pupil Size in the Glaucomatous Beagle

“…In the nonhuman primate model, peak IOP reductions were up to 35% after latanoprost and up to 27% after unoprostone (17). When unoprostone is compared to the other three commercially available prostaglandins in humans or in the dog, the drug must be instilled twice-daily to produce 24-hour IOP reductions, as the drug's effect is of less magnitude and of shorter duration (13)(14)(15)(16)(17)(20)(21)(22)(23)(33)(34)(35).…”

“…The miosis observed from unoprostone with morning dosing was not observed after the evening drug instillations, and may have resulted from the pupil returning to baseline by the following morning measurements. Experimental studies of the canine isolated sphincter muscle suggest it is sensitive to PGF ␣ , which may act directly rather than through the release of adrenergic or cholinergic neurotransmitters (32,33). The miosis that accompanied these drugs in the glaucoma Beagle appear commonly associated with the IOP changes.…”

“…In humans the once-daily prostaglandins (latanoprost, bimatoprost, and travoprost) lower IOP by approximately 6-8 mmHg (up to 50%) (1,(33)(34)(35). In the glaucomatous Beagle, these prostaglandins lower IOP by 40%-76%, and the reduction in mmHg ranges from 24-40 mmHg (20)(21)(22).…”