Evidence for the Mechanisms Underlying the Effects of Pimaradienoic Acid Isolated from the Roots of Viguiera arenaria on Rat AortaTirapelli C.R.a · Ambrosio S.R.b · da Costa F.B.c · de Oliveira A.M.d
aDepartamento de Farmacologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo; bDepartamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto; cLaboratório de Farmacognosia, Departamento de Ciências Farmacêuticas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto e dLaboratório de Farmacologia, Departamento de Física e Química, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, USP, Brazil
Do you have an account?
- Rent for 48h to view
- Buy Cloud Access for unlimited viewing via different devices
- Synchronizing in the ReadCube Cloud
- Printing and saving restrictions apply
Rental: USD 8.50
Cloud: USD 20.00
Article / Publication Details
The present study examines the effects of the diterpene ent-pimara-8(14),15-dien-19-oic acid (PA) on rat thoracic aorta. PA (10–5, 3 × 10–5 and 10–4 mol/l) caused concentration-dependent inhibition of phenylephrine (Phe)-induced contraction in either endothelium-intact or endothelium-denuded aortic rings. PA attenuated the contraction induced by CaCl2 in Ca2+-free solution containing Phe (10–7 mol/l) or KCl (30 mmol/l). This diterpene did not interfere with Ca2+ release from intracellular stores mediated by either Phe (10–6 mol/l) or caffeine (30 mmol/l). PA (10–6 to 3 × 10–4 mol/l) concentration dependently relaxed Phe-pre-contracted rings with intact (92.64 ± 7.60%) or denuded endothelium (98.82 ± 1.56%). Pre-incubation of denuded aortic rings with NG-nitro-L-arginine methyl ester (10–4 mol/l), 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (10–6 mol/l) or indomethacin (10–5 mol/l) reduced PA-induced relaxation (percentage of relaxation: 77.50 ± 3.95, 78.56 ± 2.81, 77.11 ± 6.22, respectively). However, the relaxant responses induced by PA on Phe-pre-contracted rings were unaffected by tetraethylammonium (1 and 5 mmol/l). PA also relaxed KCl-pre-contracted rings with intact (97.44 ± 3.66%) or denuded endothelium (95.95 ± 3.72%). Collectively, these results support the notion that the effects elicited by PA on vascular smooth muscle are endothelium-independent and involve extracellular Ca2+ influx blocked. In addition, PA effects are partly dependent on the release of nitric oxide from the vascular smooth muscle through an activation of guanylyl cyclase-dependent mechanism and are related to the release of metabolites derived from the arachidonic acid pathway. Finally, our results demonstrated that the PA relaxant action is not related with the opening of potassium (K+) channels.
© 2004 S. Karger AG, Basel
Article / Publication Details
Copyright / Drug Dosage / DisclaimerCopyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.