Potentiation of ATP-induced Ca(2+) mobilisation in human retinal pigment epithelial cells

Collison, David J., Tovell, Victoria E., Coombes, Laura J., Duncan, George and Sanderson, Julie (2005) Potentiation of ATP-induced Ca(2+) mobilisation in human retinal pigment epithelial cells. Experimental Eye Research, 80 (4). pp. 465-475. ISSN 1096-0007

Full text not available from this repository.

Abstract

Interaction of signalling pathways directs the functional output of many cells. This study investigated the consequences of activating adenosine and adrenergic receptors on ATP-induced Ca2+ responses in human retinal pigment epithelial (RPE) cells. Intracellular Ca2+ concentration ([Ca2+]i) of human RPE cells in primary culture was monitored using Fura-2. Cyclic adenosine monophosphate (cAMP) concentration was measured using an enzyme-linked immunosorbent assay. Both ATP and UTP (10 µm) increased [Ca2+]i in human RPE cells. Adenosine (10 nm–10 µm) had no effect on resting [Ca2+]i, but potentiated a sub-threshold response to ATP (100 nm) when ATP was added in the presence of adenosine. The potentiation occurred with other G-protein receptor agonists such as acetylcholine. Potentiation persisted in Ca-free medium, but was blocked by prior application of thapsigargin. The A1 and A2 adenosine receptor antagonists, DPCPX and MRS1706 (100 nm) respectively, inhibited potentiation in 76±7 and 23±12% of cells, respectively, but the A3 antagonist MRS1191 had no effect. Conversely, agents that activate the cAMP pathway, including isoproterenol (10 µm), forskolin (10 µm), and the protein kinase A (PKA) activator Sp-cBIMPS (1 µm), potentiated the ATP-induced response in the RPE cells. Agents that are known to inhibit the production of cAMP in other systems also caused potentiation, including clonidine (10 µm) and the Gi-activator mastoparan (10 µm). Under resting conditions, cAMP concentration in RPE cells was 7·1±0·5 pmol mg-1 protein. Isoproterenol (10 µm) and forskolin (10 µm) increased levels to 104·6±5·2 and 113·7±4·2 pmol mg-1 protein, respectively, while adenosine, clonidine, and mastoparan (all 10 µm) had no significant effect on cAMP levels. These data indicate that whilst activation of A1 and A2 adenosine receptors and a2 and ß adrenergic receptors does not influence basal Ca2+ levels, stimulation of these receptors can potentiate Ca2+ signalling by cAMP dependent and independent mechanisms in human RPE cells.

Item Type:	Article
Uncontrolled Keywords:	retina,signal transduction,calcium signalling,adenylyl cyclase
Faculty \ School:	Faculty of Science > School of Biological Sciences
UEA Research Groups:	Faculty of Science > Research Groups > Pharmaceutical Cell Biology (former - to 2017) Faculty of Science > Research Groups > Molecular and Tissue Pharmacology
Depositing User:	EPrints Services
Date Deposited:	01 Oct 2010 13:37
Last Modified:	24 Sep 2024 09:56
URI:	https://ueaeprints.uea.ac.uk/id/eprint/991
DOI:	10.1016/j.exer.2004.09.009

Actions (login required)

View Item