title: L-Citrulline, the by-product of nitric oxide synthesis, decreases vascular smooth muscle cell proliferation.
abstract: Endothelium injury plays an important role in atherosclerosis. Damage to the endothelium results in vascular smooth muscle cell proliferation. Natriuretic peptides present a potent antimitogenic action, mediating their biological effects via the binding of guanylate cyclase-linked atrial natriuretic peptide (ANP) receptor and the production of cyclic GMP. In a previous study, we demonstrated that L-citrulline, the by-product of nitric oxide synthesis, could relax rabbit aortic rings by stimulating the guanylate cyclase-linked ANP receptor. In this work, we investigated the effect of L-citrulline on vascular smooth muscle cell proliferation. L-Citrulline (10(-8) M) significantly decreased rat aortic (A10 cell line) vascular smooth muscle proliferation. The percentage of inhibition exerted by L-citrulline on days 3, 5, and 7 of the proliferation curve was 20.0 +/- 0.5%, 37.5 +/- 8.3%, and 28. 5 +/- 7.2%, respectively. In addition, L-citrulline also inhibited serum-induced DNA synthesis, measured as 5-bromo-2'-deoxyuridine incorporation. 5-Bromo-2'-deoxyuridine incorporation into nuclei of vehicle-treated cells was 40.5 +/- 2.4%, whereas in L-citrulline-treated cells the percentage decreased to 36.0 +/- 4.1%, 29.1 +/- 2.0% (P <.01, n = 4), 30.5 +/- 2.4% (P <.05, n = 4), and 23.1 +/- 0.5% (P <.001, n = 4) for 10(-10), 10(-9), 10(-8), and 10(-7) M, respectively. Zaprinast, a phosphodiesterase type V inhibitor, enhanced 5-bromo-2'-deoxyuridine incorporation in serum-stimulated cells. Moreover, L-citrulline inhibition of serum-stimulated DNA synthesis was abolished by HS-142-1 (10(-5) M), an ANP receptor antagonist. In another group of experiments, L-citrulline was shown to increase intracellular cyclic GMP levels from 2.1 +/- 0.2 pmol of cGMP/mg protein to 4.1 +/- 0.1 for L-citrulline (10(-8) M) (P <.001, n = 3). These findings suggest that L-citrulline decreases vascular smooth muscle cell proliferation in the A10 cell line by acting on DNA synthesis by mechanisms that involve the ANP receptor.
authors.affiliation: Department of Pharmacology, School of Medicine, Complutense University, Madrid, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Ruiz
authors.forename: M
authors.initials: M
authors.lastname: Del Rio
authors.forename: B
authors.initials: B
authors.lastname: Somoza
authors.forename: P
authors.initials: P
authors.lastname: Ganado
authors.forename: M
authors.initials: M
authors.lastname: Sanz
authors.forename: T
authors.initials: T
authors.lastname: Tejerina
mesh_terms: D000818:Animals; D001013:Aorta, Thoracic / Q000166:cytology / Q000187:drug effects; D002452:Cell Count; D002453:Cell Cycle / Q000502:physiology; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D002956:Citrulline / Q000378:metabolism / Q000494:pharmacology / Q000502:physiology*; D006152:Cyclic GMP / Q000378:metabolism; D004247:DNA / Q000096:biosynthesis; D006162:Guanylate Cyclase / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D009569:Nitric Oxide / Q000096:biosynthesis*; D051381:Rats
chemical_list: D002956:Citrulline; D009569:Nitric Oxide; D004247:DNA; D006162:Guanylate Cyclase; D006152:Cyclic GMP