title: Molecular mechanism of action by atrial natriuretic peptide in rat vascular smooth muscle cells.
abstract: The mechanism by which atrial natriuretic peptide (ANP) acts on cells remains obscure. Using cultured vascular smooth muscle cells (VSMC) from rat aorta, we studied the structure-activity relationship of alpha-human(h) ANP and attempted to clarify its cellular mechanism of action. Binding studies using a variety of synthetic alpha-hANP analogs with deletion and substitution of amino-acid residue(s) within the ring structure and deamino-dicarba analogs with replacement of the disulfide bond with an ethylene linkage, suggested that the original cyclic structure is a minimum requirement for biological activity and the disulfide bond is not essential for receptor binding. The present study using VSMC loaded with a fluorescent Ca2+ indicator quin-2 revealed that alpha-rat(r) ANP has no effect on increases in cytosolic free Ca2+ concentration stimulated by angiotensin (A) II or arginine-vasopressin (AVP). While both vasoconstrictive hormones rapidly stimulated phosphatidylinositol (PI) response in VSMC, pretreatment with rANP did not affect AII- or AVP-induced PI response. However, AII-stimulated phosphorylation level of 20 K-dalton (Da) myosin light chain (MLC), a regulatory contractile protein of VSMC, was attenuated by pretreatment with rANP. These data suggest that ANP may not act at site of either agonist-induced membrane PI hydrolysis or intracellular Ca2+-signal system, but may partly be involved in phosphorylation/dephosphorylation of 20 K-Da MLC in cultured rat VSMC.
authors.affiliation: Hypertension-Endocrine Division, National Cardiovascular Center Research Institute, Osaka, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Hirata
authors.forename: S
authors.initials: S
authors.lastname: Takata
authors.forename: Y
authors.initials: Y
authors.lastname: Kawahara
authors.forename: Y
authors.initials: Y
authors.lastname: Takai
authors.forename: N
authors.initials: N
authors.lastname: Chino
authors.forename: T
authors.initials: T
authors.lastname: Kimura
authors.forename: S
authors.initials: S
authors.lastname: Sakakibara
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology; D009320:Atrial Natriuretic Factor / Q000378:metabolism / Q000494:pharmacology*; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D009218:Myosins / Q000378:metabolism; D010716:Phosphatidylinositols / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D051381:Rats; D013329:Structure-Activity Relationship
chemical_list: D015220:Calcium Channels; D010716:Phosphatidylinositols; D000804:Angiotensin II; D001127:Arginine Vasopressin; D009320:Atrial Natriuretic Factor; D009218:Myosins