title: Red marine alga Bryothamnion triquetrum lectin induces endothelium-dependent relaxation of the rat aorta via release of nitric oxide.
abstract: We have investigated the vascular relaxant effects of the lectin from a red marine alga Bryothamnion triquetrum (BTL), in particular, the endothelial-dependency and the participation of a specific glycoprotein-binding site. BTL (1-100 microg mL(-1)) was applied to rat isolated aortic rings, with or without endothelium, tonically precontracted with phenylephrine (0.1 microM). Endothelium-dependent relaxation was assessed in the presence of indometacin (10 microM), L-nitro arginine methyl ester (L-NAME, 100 microM) and tetraethylammonium (TEA, 500 microM). For the involvement of the glycoprotein-binding site, BTL was assayed in presence of mucin (300 microg mL(-1)) or N-acetyl D-glucosamine (GlcNAc; 300 microg mL(-1)), a specific and non-specific lectin-binding sugar, respectively. BTL fully and concentration dependently relaxed preparations that possessed an intact endothelium (IC50 (concn producing 50% contraction) = 12.1 +/- 1.6 microg mL(-1)), whereas no significant relaxation was observed in endothelial-denuded tissue. L-NAME, but not indometacin or TEA, completely inhibited the lectin relaxation, suggesting the involvement of nitric oxide (NO). The lectin in association with mucin, but not with GlcNAc, inhibited BTL-induced relaxation, implicating the involvement of the lectin binding site. Our data suggest that the relaxant effect of the red marine alga Bryothamnion triquetrumlectin on isolated aorta occurs via interaction with a specific lectin-binding site on the endothelium, resulting in a release of NO.
authors.affiliation: Laboratório de Farmacologia dos Canais Iônicos-LAFACI, Departamento de Ciências Fisiológicas, CCS, Universidade Estadual do Ceará, 60740-000 Fortaleza-CE, Brazil.
authors.forename: Ricardo F
authors.initials: RF
authors.lastname: Lima
authors.forename: David N
authors.initials: DN
authors.lastname: Criddle
authors.forename: Emmanuel P
authors.initials: EP
authors.lastname: Souza
authors.forename: Alexandre H
authors.initials: AH
authors.lastname: Sampaio
authors.forename: Kyria S
authors.initials: KS
authors.lastname: Nascimento
authors.forename: Benildo S
authors.initials: BS
authors.lastname: Cavada
authors.forename: Ana Maria S
authors.initials: AM
authors.lastname: Assreuy
mesh_terms: D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000502:physiology; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology; D066298:In Vitro Techniques; D037102:Lectins / Q000302:isolation & purification / Q000494:pharmacology*; D008297:Male; D009126:Muscle Relaxation / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology; D009569:Nitric Oxide / Q000378:metabolism* / Q000494:pharmacology; D010936:Plant Extracts / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D011975:Receptors, Mitogen / Q000502:physiology; D000461:Rhodophyta / Q000737:chemistry*
chemical_list: D037102:Lectins; D010936:Plant Extracts; D011975:Receptors, Mitogen; D009569:Nitric Oxide