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Vascular Contraction: Effect of Age and Extracellular Calcium
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Abstract
Contractile responses to norepinephrine, serotonin and potassium chloride were determined in vitro for aortas from rats 1, 2, 3 and 12 months of age. Responses were measured under conditions of optimum length (3 cm) and resting tension (1 g). Aortic response to a maximum concentration of norepinephrine was greatest for vessels from 3-month-old rats. For all three agonists, aortas from 12-month-old rats contracted less than aortas from 2-month-old rats. The role of calcium in aortic contraction also varied with age. For rats 1–2 months of age, serotonin and potassium chloride-induced contractions were highly dependent on extracellular calcium, while norepinephrine-induced contraction showed only a slight dependence on extracellular calcium. In 12-month-old rats, all agonists were dependent on extracellular calcium for contraction. For serotonin and norepinephrine, the ability of muscle to contract in calcium-free media was decreased with age. Although the mechanism for such an altered dependence of aortic contraction on calcium has not been established, it is proposed that the utilization of extracellular calcium for contraction is not only agonist- but also age-dependent.
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158085 Blood Vessels 1976;13:139–154Copyright: 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.