DECREASED EXPRESSION OF NATRIURETIC PEPTIDE-A RECEPTORS AND DECREASEDCGMP PRODUCTION IN THE CHOROID-PLEXUS OF SPONTANEOUSLY HYPERTENSIVE RATS

Atrial natriuretic peptide receptor (ANP) subtypes and their signal tr ansduction response were characterized in choroid plexus of spontaneou sly hypertensive (SHR) and normotensive (WKY) rats. We found two ANP r eceptor subtypes, guanylate cyclase coupled and uncoupled, in both rat strains. Binding of ANP was lower in SHR choroid plexus when compared to WKY. The lower ANP binding in SHR was the result of a decrease of binding to the guanylate cyclase-coupled receptor subtype A, a decreas e that correlated well with the decreased ANP-induced cGMP formation i n SHR. Forskolin stimulated cGMP production to the same extent in both strains. In WKY rats, ANP increased basal and forskolin-stimulated cA MP production; conversely, in SHR, ANP did not affect the basal level of cAMP and inhibited the forskolin-stimulated cAMP production. These results demonstrate differences in ANP receptor subtype expression, an d ANP signal transduction in choroid plexus of hypertensive and normot ensive rats, which is of possible significance to the central mechanis ms of blood pressure control.