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      A Definite Role for the Kallikrein-Kinin System in the Renal Hemodynamic Response to an Oral Protein Load during the Aging Process

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          Abstract

          The effect of aging on the physiologic responses of renal plasma flow (RPF) and glomerular filtration rate to an acute oral protein load (renal reserve) is a poorly understood process. In this study of 37 healthy human volunteers, distributed among three groups (group 1: n = 13, age range 20–39 years; group 2: n = 13, age range 40–59 years; group 3: n = 11, age range 60–68 years), we evaluated the influence of age on some of the vasoactive systems such as plasma renin activity, urinary kallikrein, plasmatic prokallikrein, plasmatic kallikrein, and plasmatic kininogen on RPF and creatinine clearance (Ccr) in response to an acute oral protein load (1 g/kg body weight). The aging process diminished but did not cease the increments in RPF (group 1: 539.6 vs. 658.9 ml/min/1.73 m<sup>2</sup>, p < 0.001; group 2: 509.0 vs. 570.7 ml/min/ 1.73 m<sup>2</sup>, p < 0.001; group 3: 453.9 vs. 506.0 ml/min/ 1.73 m<sup>2</sup>, p < 0.001) and Ccr (group 1: 139.7 vs. 166.5 ml/ min/1.73 m<sup>2</sup>, p < 0.001; group 2: 126.6 vs. 142.2 ml/min/1.73 m<sup>2</sup>, p < 0.001; group 3: 112.6 vs. 121.4 ml/min/ 1.73 m<sup>2</sup>, p < 0.01) after a protein overload. The plasma renin activity did not change after a meat meal. On the other hand, all parameters regarding the kinin system changed significantly in the direction of increased bradykinin formation, despite aging (urinary kallikrein – group 1: 0.25 vs. 0.44 mU/ml, p < 0.005; group 2: 0.25 vs. 0.41 mU/ml, p < 0.005; group 3: 0.33 vs. 0.47 mU/ml, p < 0.005/plasmatic kininogen – group 1: 1.3 vs. 0.9 µg LBK/ml, p < 0.005; group 2: 1.1 vs. 0.7 µg LBK/ml, p < 0.005; group 3: 0.8 vs. 0.7 µg LBK/ml, p < 0.005). These findings indicate that: (1) the aging process narrows but does not cease the increment range in Ccr and RPF after acute oral protein ingestion; (2) increased bradykinin formation plays a definite role in the acute renal vasodilatory response, and (3) contrary to previous clinical studies, our results suggest that the renal reserve is progressively and significantly reduced during the aging process.

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          Most cited references 2

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          Renal functional reserve in humans

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            Changes with age in the human kidney

             V.K. Goyal (1982)
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              Author and article information

              Journal
              NEF
              Nephron
              10.1159/issn.1660-8151
              Nephron
              S. Karger AG
              1660-8151
              2235-3186
              1999
              December 1999
              30 November 1999
              : 83
              : 4
              : 308-313
              Affiliations
              Hypertension Clinic of the Laboratory of Clinical and Experimental Pathophysiology – Clinex, Rio de Janeiro State University, Rio de Janeiro, Brazil
              Article
              45422 Nephron 1999;83:308–313
              10.1159/000045422
              10575292
              © 1999 S. Karger AG, Basel

              Copyright: 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.

              Page count
              Figures: 2, Tables: 2, References: 29, Pages: 6
              Product
              Self URI (application/pdf): https://www.karger.com/Article/Pdf/45422
              Categories
              Original Paper

              Cardiovascular Medicine, Nephrology

              Kallikrein-kinin system, Aging, Renal hemodynamics, Renal reserve

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