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- Title
Common Actions of Adenosine Receptor Agonists in Modulating Human Trabecular Meshwork Cell Transport.
- Authors
J. C. Fleischhauer; C. H. Mitchell; W. D. Stamer; M. O. Karl; K. Peterson-Yantorno; M. M. Civan
- Abstract
A 1 adenosine receptors (ARs) reduce, and A 2ARs increase intraocular pressure, partly by differentially altering resistance to aqueous humor outflow. It is unknown whether the opposing effects of A 1AR and A 2AR agonists are mediated at different outflow-pathway cell targets or by opposing actions on a single cell target. We tested whether a major outflow-pathway cell, the trabecular meshwork (TM) cell might constitute the primary AR-agonist target and respond differentially to A 1, A 2A and A 3AR agonists. Receptor activation in human TM cells was identified by applying subtype-selective AR agonists: CPA and ADAC for A 1ARs, CGS 21680 and DPMA for A 2AARs, and Cl-IB-MECA and IB-MECA for A 3ARs. Stimulation of A 1, A 2A and A 3ARs elevated Ca 2+, measured with fura-2. Whole-cell patch clamping indicated that AR agonists activated ion channels non-uniformly, possibly reflecting variability in magnitude of agonist-triggered second-messenger responses. A 1, A 2A and A 3AR agonists all reduced volume, determined by calcein cell imaging. The endogenous source of adenosine delivery to the outflow pathway could be the TM cells since these cells were stimulated to release ATP by hypotonic perfusion. We conclude that: (1) TM cells express functional A 1, A 2A and A 3ARs; and (2) the reported differential effects of AR agonists on aqueous humor outflow are not mediated by differential actions on TM-cell Ca 2+ and volume, but likely by actions on separate cell targets.
- Subjects
ADENOSINES; INTRAOCULAR pressure; CELLS
- Publication
Journal of Membrane Biology, 2003, Vol 193, Issue 2, p121
- ISSN
0022-2631
- Publication type
Article
- DOI
10.1007/s00232-002-2013-5