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Effect of a crude extract of Mandevilla velutina on contractions induced by bradykinin and [des‐Arg 9 ]‐bradykinin in isolated vessels of the rabbit
Author(s) -
Calixto João B.,
Yunes Rosendo A.
Publication year - 1986
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1986.tb16269.x
Subject(s) - bradykinin , chemistry , contraction (grammar) , incubation , aorta , endocrinology , pentobarbital , medicine , pharmacology , biochemistry , biology , receptor
1 The effect of a crude aqueous/alcoholic extract of Mandevilla velutina on the contractile responses induced by bradykinin (Bk), [des‐Arg 9 ]‐Bk and noradrenaline (NA) in rings of arterial and venous rabbit vessels was analysed. 2 The contractile responses induced by Bk, [des‐Arg 9 ]‐Bk differed between the rings of the aorta, jugular and mesenteric veins. Rings of the aorta and mesenteric vein were stimulated by both peptides, but were more sensitive to [des‐Arg 9 ]‐Bk. The jugular vein was not only more sensitive to Bk but also did not respond to [des‐Arg 9 ]‐Bk, even in the presence of a high concentration of this peptide. 3 Pre‐incubation for 20 min with the crude extract of Mandevilla velutina rhizomes (1 mg ml −1 ) antagonized the contractions produced by both peptides. This blockade was surmountable by about a 10–30 fold increase in the concentration of both Bk and [des‐Arg 9 ]‐Bk. In the aorta and mesenteric vein the NA‐induced contractions were not affected by 1 mg ml −1 of the extract. 4 Bk (1 to 100 n m ) caused a concentration‐related contractile response in rings of the rabbit jugular vein. Incubation for 20 min with the crude extract (0.25−1 mg ml −1 ) caused a concentration‐dependent displacement to the right of the Bk concentration‐response curves and depressed the maximal response. 5 The onset of action of the crude extract was rapid and was reversible after intermittent washing of the preparations for 30–60 min. 6 These findings confirm and extend our previous work and indicate that the crude extract of Mandevilla velutina selectively antagonizes the action of Bk and related peptides on both B 1 ‐ and B 2 ‐receptors present in rabbit vascular muscle.