eng Science and Education Publishing Journal of Food and Nutrition Research 2333-1240 2023-08-16 11 8 519 524 10.12691/jfnr-11-8-1 JFNR20231181 article Jair Lozano-Cuenca 1 Oscar Alberto L¨®pez-Canales 2 ¨¢ngel Miliar-Garc¨ªa 3 Mar¨ªa de los ¨¢ngeles Mart¨ªnez¨CGod¨ªnez 3 Osiris Teran-Gallardo 3 Mar¨ªa Cristina Paredes-Carbajal 3 Ruth Mery L¨®pez-Mayorga 3 Enrique Fernando Castillo-Henkel 3 H¨¦ctor Flores-Herrera 4 Jorge Skiold L¨®pez-Canales skiold666@hotmail.com 4 4 Departamento de Fisiolog¨ªa y Desarrollo Celular, Instituto Nacional de Perinatolog¨ªa, Montes Urales 800, Col. Lomas Virreyes, Deleg. Miguel Hidalgo, C.P. 11000, Ciudad de M¨¦xico, M¨¦xico Departamento de Fisiolog¨ªa. Facultad de medicina. Universidad Nacional Aut¨®noma de M¨¦xico. Ciudad de M¨¦xico, M¨¦xico Secci¨®n de estudios de posgrado e investigaci¨®n, Escuela Superior de Medicina, Instituto Polit¨¦cnico Nacional, Plan de San Luis and Salvador D¨ªaz Mir¨®n, Ciudad de M¨¦xico, M¨¦xico Departamento de Inmuno-Bioqu¨ªmica, Instituto Nacional de Perinatolog¨ªa, Montes Urales 800, Colonia Lomas Virreyes, 11000, Ciudad de M¨¦xico, M¨¦xico The aim of this study was to gain further insights into the mechanisms responsible for the Val-Pro-Pro-induced vasodilation of rat aortic rings. The vasorelaxant effect was found at 10-9-10-4 M of the tripeptide on phenylephrine-precontracted rings. It was endothelium-dependent and concentration-dependent at the higher concentrations. The vasodilator response was not modified by preincubation with 3.1 x 10-7 M glibenclamide, 10-3 M 4-aminopyridine (4-AP), 10-5 M indomethacin or 10-5 M cycloheximide. However, this response was significantly diminished by preincubation with 10-5 M L-NG-Nitroarginine methyl ester (L-NAME), 10-7 M 1H-(1,2,4)oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), 10-6 M (9S,10R,12R)-2,3,9,10,11,12-hexahydro-10-methoxy-2,9-dimethyl-1-oxo-9,12-epoxy-1H-diindolo[1,2,3-fg:3',2',1'-kl]pyrrolo[3,4-i]benzodiazocine-10-carboxylic acid, methyl ester (KT 5823), 10-2 M tetraethylammonium (TEA) and 10-7 M apamin plus 10-7 M charybdotoxin, as well as by the removal of the vascular endothelium. Apparently, Val-Pro-Pro directly produced vasorelaxation of phenylephrine-precontracted rat aortic rings by stimulating the vascular endothelium and activating the NO/cGMP/PKG/Ca2+-activated K+ channel pathway. http://pubs.sciepub.com/jfnr/11/8/1/jfnr-11-8-1.pdf bioactive peptides nitric oxide potassium channels rat aorta vascular endothelium