Gossell-Williams, Maxine D.; Simon, Oswald R.; Melville T.; Evans, R.
Author Affiliation, Ana.
Department of Basic Medical Sciences
An aqueous extract from the bark of Fagara martinicensis shows selective stimulation of a1-adrenergic receptors [Abstract]
Experimental Biology 2004: Meeting Abstracts
Date of Publication
An infusion from the bark of Fagara martinicensis (Rutaceae) is claimed in folklore to have antispasmodic activity. This potential was examined using an aqueous bark extract (FM) on different smooth muscle preparations. Isometric tension was measured in isolated organ bath preparations of the guinea-pig ileum, the prostatic portion of rat vas deferens in the absence and presence of electrical field stimulation (0.1 Hz, 2ms, 30V) and rings from the thoracic portion of the rat aorta. Contrary to folklore claims, FM contracted all smooth muscle preparations used. The contractions of the vas deferens and aortic ring were further examined. Concentrations of FM less than 4.1 mg/ml did not directly contract the vas deferens, but, reduced the height of the twitch contractions developed in response to electrical field stimulation. This reduction was not inhibited by yohimbine (8mM), an a2- adrenoreceptor antagonist (pA2=7.46- 7.88). Direct contraction of the va deferens was observed at higher concentrations of FM(4.1-14.1 mg/ml) and inhibited by prazosin (60 hM), an a1- adrenoreceptor antagonists (pA2=9.4). In the aorta, the contraction produced by FM (0.01-9.38 mg/ml) was also inhibited by prazosin (4.28 and 8.57 hM). We conclude that Fagara martinicensis contains compound(s) that stimulate a1- adrenoreceptor and may be selective, since FM did not affect presynaptic a2- adrenoreceptors.....