Blockade of kinin-induced responses of the guinea-pig isolated urinary bladder by the extract of Mandevilla velutina.
1. The crude extract (CE) from M. velutina (0.2-0.8 mg/ml), antagonized in a dose-dependent and reversible manner bradykinin (BK)- and lysyl-BK-induced contractions of the guinea-pig urinary bladder in vitro. 2. Schild plots yielded nominal pA2 values (as g/ml) of 3.5 and 3.7, but the slopes were significantly greater than unity. 3. At concentrations 2-10-fold higher, the CE failed to affect responses to acetylcholine or histamine. 4. In electrically-stimulated tissue, BK, L-BK and M-L-BK potentiated nerve-mediated twitch responses and increased muscular tone. The B1 agonist [des-Arg9]-BK, was inactive up to 10 microM. 5. The CE from M. velutina (0.4 mg/ml) inhibited both actions of the kinins.
Calixto
J B
JB
Department of Pharmacology (CCB), Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil.
Yunes
R A
RA
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001920:Bradykinin / Q000031:analogs & derivatives / Q000494:pharmacology; D004558:Electric Stimulation; D004594:Electrophysiology; D005260:Female; D006168:Guinea Pigs; D006632:Histamine / Q000494:pharmacology; D066298:In Vitro Techniques; D007609:Kallidin / Q000037:antagonists & inhibitors / Q000494:pharmacology; D007705:Kinins / Q000037:antagonists & inhibitors*; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects*; D010936:Plant Extracts / Q000494:pharmacology*; D001743:Urinary Bladder / Q000187:drug effects
D007705:Kinins; D010936:Plant Extracts; D007609:Kallidin; C018103:bradykinin, Met-Lys-; D006632:Histamine; D000109:Acetylcholine; D001920:Bradykinin