Studies on the mechanism of spasmolytic activity of (O-methyl-) -N- (2,6-dihydroxybenzoyl) tyramine, a constituent of Aniba riparia (Nees) Mez. (Lauraceae) , in rat uterus, rabbit aorta and guinea-pig alveolar leucocytes
Thomas, G.; Branco, U.J.; Barbosa Filho, J.M.; Bachelet, M.; Vargaftig, B.B.
Journal of Pharmacy and Pharmacology 46(2): 103-107
1994
ISSN/ISBN: 0022-3573 PMID: 8021798 Document Number: 434138
The mechanism of action of a nonspecific smooth muscle relaxant, (O-methyl)-N-(2,6-dihydroxybenzoyl)tyramine (riparin), isolated from the unripe fruits of A. riparia, was studied in relation to Ca2+ metabolism in smooth muscle tissues and guinea-pig alveolar leukocytes. Riparin inhibited Ca2+ entry through Ca2+ channels in the depolarized rat uterus. It inhibited intracellular calcium-dependent transient contractions of the aorta induced by noradrenaline. Riparin also inhibited ionophore A23187-promoted intracellular Ca2+ accumulation in guinea-pig leukocytes. It is suggested that the spasmolytic activity of riparin is due to the inhibition of Ca2+ influx and of Ca2+ release from intracellular stores.