Effects of UDP on ARPE cells: possible involvement of P2Y6 receptors

Abstract

Purpose: We have studied the effects of nucleotides (ATPγS, UTP and UDP) on human retinal pigmental cells, in relation to their expression of functional P2Y receptors. Methods: ARPE cells were grown in culture and stimulated with ATPγS, UTP and UDP. Cell proliferation was analysed by BrdU incorporation. Calcium flux and cAMP were measured by fluorometry and radio‐immunoassay. IL‐8 production was investigated by semi‐quantitative RT‐PCR and ELISA. P2Y2, P2Y4 and P2Y6 expression was analysed by RT‐PCR. Results: UDP inhibited ARPE cell proliferation while ATPγS slightly stimulated it and UTP had no effect. This differential effect suggests the expression of other P2Y receptors than the already described P2Y2. Accordingly we detected transcripts for the P2Y6 receptor, which is a UDP receptor. UDP induced a calcium flux, like ATPγS and UTP, but no cAMP production. All nucleotides stimulated IL‐8 secretion. Conclusions: Our results suggest that ARPE cells express functional P2Y6 receptors.