advertisement
Abstract #5438 Published in IGR 1-2
Systemic and ocular vascular roles of the antiglaucoma agents β-adrenergic antagonists and Ca2+ entry blockers
Dao-Yi Yu; Er-Ning Su; Cringle SJ; Alder VA; Yu PK; DeSantis LSurvey of Ophthalmology 1999; 43 (S1): S214-S222
This review addresses whether the antiglaucoma agents ß-adrenergic antagonists and Ca2+ entry blockers cause vasoactive effects in the retinal and other vasculatures, as they do in other tissues. The potent vasodilating effects of Ca2+ entry blockers on ocular vessels have recently been demonstrated in in vivo and in vitro studies, implying that the maintenance of ocular vascular tone relies almost exclusively on extracellular Ca2+. Ca2+ entry blockers may potentially play a role in relaxing the retinal, long posterior ciliary, and ophthalmociliary arteries, to improve the ocular circulation in vascular diseases in which there is considerable vascular tone present. The ß-adrenergic antagonists are discussed with reference to their antihypertensive role, their effect on other vascular beds, and finally what is known of their effect in the ocular vasculature. The emerging evidence that particular selective ß-adrenergic antagonists, such as betaxolol, are also potent Ca2+ channel entry blockers in other vascular beds is presented. Betaxolol has been shown to induce vasodilatation in the retinal and other ocular vascular beds, although studies have shown that ß1-adrenergic receptors are sparse in these vascular beds. This implies than an alternative mechanism must be responsible for betaxolol-induced vasodilatation. Evidence is presented that betaxolol vasodilates via its potent Ca2+ channel entry blocking properties, and its potency and ability to vasodilate are compared with those of nimodipine and timolol, as well as with those of other Ca2+ channel entry blockers. Important areas for future research in this area are discussed.
Dao-Yi Yu, Lions Eye Institute and Centre for Ophthalmology and Visual Science, University of Western Australia, Nedlands, WA; Australia
Classification:
11.7 Treatment of bloodflow (Part of: 11 Medical treatment)
