FUNCTIONAL INVOLVEMENT OF M1 AND M3 MUSCARINIC RECEPTOR SUBTYPES IN ACETYLCHOLINE (ACH)-INDUCED VASOCONSTRICTION IN HUMAN UMBILICAL VEIN (HUV).

PUJOL LEREIS, VIRGINIA A; HITA, FRANCISCO J; RODRÍGUEZ, MARÍA C; ROTHLIN, RODOLFO P.

Mar del Plata, Hotel 13 de Julio, Argentina.

Congreso; XXXVII REUNION ANUAL DE LA SOCIEDAD ARGENTINA DE FARMACOLOGÍA EXPERIMENTAL; 2005

SOCIEDAD ARGENTINA DE FARMACOLOGÍA EXPERIMENTAL

Introduction: The present study attempted to characterizepharmacologically the muscarinic receptor subtypesmediating contraction of HUV. Methods and results: HUVrings were placed under isometric tension in Krebs solutionat 37ºC. After 2.5 h, concentration response curves (CRC)to ACh or McN-A-343 (M1 receptor selective agonist) wereobtained in the presence or absence of different antagonist(applied 60 min before CRC). CRC to ACh wereantagonized by several compounds: atropine (nonselectivemuscarinic receptors antagonist; pKB 9.75),pirenzepine (M1 receptors antagonist; calculated pA2 7.58),methoctramine (M2 receptors antagonist; pKB 6.78) andpFHHSiD (M3 receptors antagonist; calculated pA27.94).PD102807 (M4 receptors antagonist) was ineffectiveagainst ACh. Simultaneous exposure to pirenzepine andpFHHSiD produced a greater inhibition of Ach-CRC thanobtained in conditions of individual antagonism. McN-A-343produced a similar maximal response but a less potent onethan ACh. The pA2 estimated for pirenzepine against McNA-343 was 8.54. Conclusion: The data obtained in thisstudy demonstrates the role of M1 muscarinic receptorsubtypes and suggest the involvement of M3 muscarinicreceptor subtypes in ACh-induced vasoconstriction in HUV.