Effects of a topical α2 adrenergic agonist on ciliary blood flow and aqueous production in rabbits

H. A. Reitsamer, M. Posey, J. W. Kiel

Research output: Contribution to journalArticle

43 Citations (Scopus)

Abstract

The relationship between ciliary perfusion and aqueous production is poorly understood. It was recently reported that aqueous production decreases when ciliary blood flow is reduced by lowering the ocular perfusion pressure, and hypothesized that drug-induced reduction of ciliary blood flow would also decrease aqueous production. In the present study, we test this hypothesis with an α2 adrenergic agonist (brimonidine) formulated for topical application. When used acutely, brimonidine decreases intraocular pressure (IOP) by suppressing aqueous production, although its mechanism of action is unclear. The experiments were performed in four groups of anesthetized rabbits (n=33) in which the following variables were measured: ocular mean arterial pressure (OMAP), IOP, orbital venous pressure (OVP), aqueous flow, ciliary blood flow, ciliary oxygen tension (PO2), episcleral venous pressure (EVP), carotid blood flow and heart rate. The measurements were made before and after brimonidine (0.15%, 40 μl) was applied to the cornea. Brimonidine decreased IOP (-33%, p<0.01), aqueous flow (-39%, p<0.01), ciliary blood flow (-37%, p<0.01), EVP (-42%, p<0.01) and ciliary PO2 (-32%, p<0.05). We conclude that topical brimonidine is a ciliary vasoconstrictor, and that α2 adrenergic agonist-induced decreases in ciliary blood flow decrease aqueous production.

Original languageEnglish (US)
Pages (from-to)405-415
Number of pages11
JournalExperimental Eye Research
Volume82
Issue number3
DOIs
StatePublished - Mar 2006

Fingerprint

Adrenergic Agonists
Venous Pressure
Rabbits
Intraocular Pressure
Perfusion
Vasoconstrictor Agents
Cornea
Arterial Pressure
Heart Rate
Brimonidine Tartrate
Oxygen
Pressure
Pharmaceutical Preparations

Keywords

  • Brimonidine
  • Episcleral venous pressure
  • Intraocular pressure homeostasis
  • Ocular hydrodynamics
  • Oxygen

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems

Cite this

Effects of a topical α2 adrenergic agonist on ciliary blood flow and aqueous production in rabbits. / Reitsamer, H. A.; Posey, M.; Kiel, J. W.

In: Experimental Eye Research, Vol. 82, No. 3, 03.2006, p. 405-415.

Research output: Contribution to journalArticle

Reitsamer, H. A. ; Posey, M. ; Kiel, J. W. / Effects of a topical α2 adrenergic agonist on ciliary blood flow and aqueous production in rabbits. In: Experimental Eye Research. 2006 ; Vol. 82, No. 3. pp. 405-415.
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