MESSENGER-RNAS ENCODING THE NATRIURETIC PEPTIDES AND THEIR RECEPTORS ARE EXPRESSED IN THE EYE

The rates of secretion and removal of aqueous humour are major determi nants of intraocular pressure (IOP). The natriuretic peptides, atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP) and C-type natriuretic peptide (CNP) are vasodilators with variable effects on el ectrolyte and water transport at sites such as the nephron. There is s ome evidence that they may also affect fluid balance in the eye. As a first step in understanding the function of these peptides in the eye, we have used the technique of cDNA amplification with the polymerase chain reaction to demonstrate the presence of mRNA transcripts encodin g the three natriuretic peptide receptors (NPR-A, NPR-B and NPR-C) in the retina, choroid and ciliary process of the rat and rabbit eye. In addition we have observed a differential distribution of ANP, BNP and CNP mRNAs in ocular tissues suggesting that at least part of the natri uretic peptide immunoreactivity detected in the eye arises from local synthesis of peptide. Thus, the eye appears to be able to synthesize a ll the components of the natriuretic peptide system necessary to modul ate IOP independently of changes in the plasma concentrations of these peptides. (C) 1995 Academic Press Limited