Published Online
on June 19, 2006

A more recent version of this article appeared on August 1, 2006

This Article Full Text (PDF) All Versions of this Article: 48/2/329    most recent 01.HYP.0000229906.27330.4fv1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Raj, S. R. Articles by Robertson, D. Search for Related Content PubMed PubMed Citation Articles by Raj, S. R. Articles by Robertson, D. Related Collections Other hypertension Other Treatment

Submitted on March 31, 2006
Revised on April 21, 2006

Sodium Paradoxically Reduces the Gastropressor Response in Patients With Orthostatic Hypotension

Satish R. Raj^*; Italo Biaggioni; Bonnie K. Black; Aniket Rali; Jens Jordan; Indu Taneja; Paul A. Harris; and David Robertson

From the Autonomic Dysfunction Center, Division of Clinical Pharmacology (S.R.R., I.B., B.K.B., A.R., I.T., D.R.), Departments of Medicine (S.R.R., I.B., D.R.), Pharmacology (S.R.R., I.B., I.T., D.R.), Neurology (D.R.), and Biomedical Informatics (P.A.H.), Vanderbilt University, Nashville, Tenn; and Franz-Volhard Clinical Research Center (J.J.), Medical Faculty of the Charité and Helios Klinikum, Berlin, Germany.

^* To whom correspondence should be addressed. E-mail: satish.raj{at}vanderbilt.edu.

Abstract--Orthostatic hypotension (OH) can cause syncope that is difficult to treat. We have found that 473 mL (16 oz) of water can increase systolic blood pressure (SBP) by >30 mm Hg in many OH patients (the gastropressor response). OH patients are routinely advised to increase their sodium intake to augment their blood volume. We tested the hypothesis that the ingestion of salt with water would increase the magnitude of the acute pressor response compared with water alone in patients with OH. Patients with OH (n=9; female=5; 65±3 years) underwent a randomized crossover trial of drinking water (H₂O) and salt water (NaCl-H₂O). Noninvasive heart rate and BP were measured with the patient seated for 60 minutes after ingestion. The area under the curve for SBP was greater with H₂O than NaCl-H₂O for the 30 minutes (714±388 mm Hgxmin versus 364±369 mm Hgxmin; P=0.002) and 60 minutes (1454±827 mm Hgxmin versus 812±734 mm Hgxmin; P=0.048) after ingestion. The increase in SBP with H₂O was greater than with NaCl-H₂O at 30 minutes (37±6 versus 18±5 mm Hg; P=0.006) but not at 60 minutes (17±6 versus 10±6 mm Hg; P=0.4). Norepinephrine increased after H₂O (P=0.018) but not after NaCl-H₂O (P=0.195). Both oral water and salt water increase BP in patients with OH. Instead of augmenting the gastropressor response, the additional salt paradoxically attenuates the pressor response to water. These data suggest a potentially important role for gastrointestinal osmolality in the activation of the sympathetic nervous system leading to cardiovascular reflexes responsible for the gastropressor response.

Key words: blood pressure • sympathetic nervous system • sodium • hypotension • autonomic nervous system • water-electrolyte balance

This article has been cited by other articles:

				M. Boschmann, J. Steiniger, G. Franke, A. L. Birkenfeld, F. C. Luft, and J. Jordan Water Drinking Induces Thermogenesis through Osmosensitive Mechanisms J. Clin. Endocrinol. Metab., August 1, 2007; 92(8): 3334 - 3337. [Abstract] [Full Text] [PDF]

				M. V. Dzurik, A. Diedrich, B. Black, S. Y. Paranjape, S. R. Raj, D. W. Byrne, and D. Robertson Endogenous substance P modulates human cardiovascular regulation at rest and during orthostatic load J Appl Physiol, June 1, 2007; 102(6): 2092 - 2097. [Abstract] [Full Text] [PDF]

				S. R. Ferreira Filho, F. de Castro Rodrigues Ferreira, P. C. Oliveira, and M. A. Nery Systemic Hemodynamic Changes in Older Hypertensive Patients After Drinking Water or Eating a Meal Hypertension, May 1, 2007; 49(5): e31 - e31. [Full Text] [PDF]

				S. R. Raj, I. Biaggioni, and D. Robertson Response to Systemic Hemodynamic Changes in Older Hypertensive Patients After Drinking Water or Eating a Meal Hypertension, May 1, 2007; 49(5): e32 - e32. [Full Text] [PDF]