HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 288/5/R1211    most recent 00244.2004v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (4) Citing Articles via Google Scholar Google Scholar Articles by Bealer, S. L. Search for Related Content PubMed PubMed Citation Articles by Bealer, S. L.

WATER AND ELECTROLYTE HOMEOSTASIS

Increased dietary sodium inhibits baroreflex-induced bradycardia during acute sodium loading

Department of Pharmacology and Toxicology, College of Pharmacy, University of Utah, Salt Lake City, Utah

Submitted 4 April 2004 ; accepted in final form 22 December 2004

The present study investigated the effects of increased dietary sodium on the modification of cardiac baroreflex responses induced by acute sodium loading. Changes in blood pressure and heart rate during intravenous phenylephrine and nitroprusside administration were compared using a four-parameter sigmoid logistic function before and after a 30-min infusion of 0.6 or 1.0 M NaCl in conscious male Sprague-Dawley rats consuming only tap water (Tap) or isotonic saline (Iso) for 2–3 wk. In Tap animals, infusion of 1.0 M NaCl increased the baroreflex-induced heart rate minimum, reduced heart rate range, and increased the operating blood pressure. In contrast, infusion of 0.6 M NaCl in Tap rats reduced both heart rate minimum and maximum. However, infusion of 0.6 M NaCl in Iso animals produced responses similar to that shown in Tap rats infused with 1.0 M NaCl. In addition, the decreased heart rate minimum in Tap rats after infusion of 0.6 M NaCl was prevented by intravenous administration of a vasopressin V₁-receptor antagonist. Furthermore, cardiac parasympathetic responses were similar in Tap and Iso rats before and after 0.6 M NaCl infusion. However, in animals receiving intravenous atropine, 0.6 M NaCl decreased heart rate minimum and maximum in Tap but did not alter the response parameters in Iso rats. These results demonstrate that the facilitation of cardiac baroreflex responses normally observed during moderate sodium loading is mediated by vasopressin and that increased dietary sodium ingestion reverses this facilitation by reducing sympathetic nervous system withdrawal.

hypertension; cardiac baroreceptor

This article has been cited by other articles:

				P. Shi, M. A. Martinez, A. S. Calderon, Q. Chen, J. T. Cunningham, and G. M. Toney Intra-carotid hyperosmotic stimulation increases Fos staining in forebrain organum vasculosum laminae terminalis neurones that project to the hypothalamic paraventricular nucleus J. Physiol., November 1, 2008; 586(21): 5231 - 5245. [Abstract] [Full Text] [PDF]

				P. Shi, S. D. Stocker, and G. M. Toney Organum vasculosum laminae terminalis contributes to increased sympathetic nerve activity induced by central hyperosmolality Am J Physiol Regulatory Integrative Comp Physiol, December 1, 2007; 293(6): R2279 - R2289. [Abstract] [Full Text] [PDF]

				R. A. Khalil Dietary salt and hypertension: new molecular targets add more spice Am J Physiol Regulatory Integrative Comp Physiol, March 1, 2006; 290(3): R509 - R513. [Full Text] [PDF]