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Abstract #5409 Published in IGR 1-2
In vitro studies of the effects of β-adrenergic drugs on retinal and posterior ciliary microarteries
Hoste AMSurvey of Ophthalmology 1999; 43 (S1): S183-S190
The small-vessel myograph allows for precise measurements of physiopharmacologic responses of the ocular microarteries under controlled conditions. Studies the myograph have shown that ß-adrenergic agonists are unable to induce significant relaxation in retinal and posterior ciliary microarteries, indicating that these microarteries have very few or no functional ß-adrenoceptors. Thus, ß-blockers would not be expected to have important adverse vasoconstrictory effects in the posterior part of the eye that are caused by their ß-adrenoceptor binding capacities. On the contrary, some ß-blockers, such as propranolol (the standard ß-blocker in pharmacology) and betaxolol (a ß-blocker used in ophthalmology), have vasorelaxant effects, probably a result of their Ca2+ channel-blocking activity. This activity shows no stereospecificity. Betaxolol could thus act as a vasodilator in glaucoma patients, on the condition that it penetrates into the posterior part of the eye after topical application. If so, it could also induce vasodilatation in circumstances of vascular endothelium injury, because this effect is endothelium-independent.
A.M. Hoste, Department of Human Physiology and Pathophysiology, University of Antwerp, Antwerp; Belgium
Classification:
11.3.4 Betablocker (Part of: 11 Medical treatment > 11.3 Adrenergic drugs)
