title: Cyclic GMP down-regulates atrial natriuretic peptide receptors on cultured vascular endothelial cells.
abstract: Down-regulation of atrial natriuretic peptide (ANP) receptors was investigated using a cultured bovine pulmonary artery endothelial (CPAE) cell line. Endothelial cells have been shown to possess two subtypes of ANP receptors, a guanylate cyclase-coupled receptor (B-receptor) and a clearance receptor (C-receptor). The treatment with APIII, rat ANP (103-126), at concentrations of 10(-8) to 10(-6) M for 24 h, resulted in a significantly (p less than 0.01) greater decrease in maximum 125I-APIII binding to CPAE cells than the identical concentration of API, rat ANP (103-123). APIII at concentrations of 10(-8) to 10(-6) M stimulated cyclic GMP (cGMP) production 3.3-17.5-fold greater than similar concentrations of API. From these findings, we hypothesized that cGMP produced following ANP binding to the B-receptor participates in ANP receptor regulation. M&B 22948, a selective inhibitor of cGMP-specific phosphodiesterase, significantly (p less than 0.01) potentiated the effect of both API and APIII on 125I-APIII binding, while M&B 22948 itself had no significant effect on 125I-APIII binding. Treatment of the cells with 1 mM 8-bromo-cGMP also significantly (p less than 0.01) decreased 125I-APIII binding to the cells, and a potentiation of this effect was observed by M&B 22948. Scatchard analysis of binding data from 8-bromo-cGMP-treated cells showed a significant decrease in Bmax (1.79 +/- 0.15 to 1.20 +/- 0.07 fmol/mg protein, p less than 0.05) without a significant change in Kd. Affinity cross-linking of 125I-APIII to 8-bromo-cGMP-treated cells showed a decrease in the labeling of 60- and 70-kDa bands corresponding to the C-receptor. In addition, the APIII-stimulated cGMP response remained unchanged in the 8-bromo-cGMP-treated cells, indicating that the B-receptor was not down-regulated. We conclude that cGMP regulates ANP-binding sites on the endothelial cell and that the evidence indicates that the C-receptor may preferentially be down-regulated by cGMP in CPAE cells.
authors.affiliation: Department of Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, Charleston 29425.
authors.forename: J
authors.initials: J
authors.lastname: Kato
authors.forename: K L
authors.initials: KL
authors.lastname: Lanier-Smith
authors.forename: M G
authors.initials: MG
authors.lastname: Currie
mesh_terms: D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000378:metabolism*; D001345:Autoradiography; D002417:Cattle; D002460:Cell Line; D003432:Cross-Linking Reagents; D006152:Cyclic GMP / Q000031:analogs & derivatives / Q000378:metabolism* / Q000494:pharmacology; D015536:Down-Regulation; D004591:Electrophoresis, Polyacrylamide Gel; D004730:Endothelium, Vascular / Q000378:metabolism*; D011688:Purinones / Q000494:pharmacology; D051381:Rats; D017461:Receptors, Atrial Natriuretic Factor; D011956:Receptors, Cell Surface / Q000378:metabolism*
chemical_list: D003432:Cross-Linking Reagents; D011688:Purinones; D011956:Receptors, Cell Surface; D015124:8-Bromo Cyclic Adenosine Monophosphate; C016276:8-bromocyclic GMP; D009320:Atrial Natriuretic Factor; D017461:Receptors, Atrial Natriuretic Factor; C011145:zaprinast; D006152:Cyclic GMP