The present experiments examined whether in rats consuming diets with either high NaCl content (8%) or low Na⁺ content (0.01%) for 2 wk excitatory inputs to the rostral ventrolateral medulla (RVLM) would be altered. In chloralose-anesthetized rats, injection of glutamate into the RVLM elicited a pressor response that, compared with rats fed a control diet, was 50% larger in rats fed a diet containing 8% NaCl and was 25% smaller in rats fed a diet containing 0.01% Na⁺. Pressor responses produced by electrical stimulation of sciatic nerve afferents, as well as by microinjections into the RVLM of L-dihydroxyphenylalanine or carbachol, were all potentiated by high dietary salt intake and reduced by low dietary salt intake. Dietary salt intake had no effect on pressor responses produced by intravenous injection of phenylephrine, indicating that salt-related alterations in cardiovascular responses produced by central activation could not be accounted for by changes in peripheral vascular reactivity. The decrease in arterial pressure produced by injection of glutamate into the nucleus of the solitary tract was also potentiated by the high salt diet, suggesting that the sensitivity of central baroreceptor reflex pathways may be altered by dietary NaCl. These results indicate that the amount of NaCl consumed in the diet can change the sensitivity of RVLM sympathoexcitatory neurons, and this change in sensitivity is not restricted to any particular class of cell surface receptors.

excitatory amino acid; somatic pressor response; baroreceptor reflex; hypertension; arterial blood pressure

This article has been cited by other articles:

				J. M. Adams, C. J. Madden, A. F. Sved, and S. D. Stocker Increased Dietary Salt Enhances Sympathoexcitatory and Sympathoinhibitory Responses From the Rostral Ventrolateral Medulla Hypertension, August 1, 2007; 50(2): 354 - 359. [Abstract] [Full Text] [PDF]

				P. J. Mueller and E. M. Hasser Putative role of the NTS in alterations in neural control of the circulation following exercise training in rats Am J Physiol Regulatory Integrative Comp Physiol, February 1, 2006; 290(2): R383 - R392. [Abstract] [Full Text] [PDF]

				S. L. Bealer Increased dietary sodium inhibits baroreflex-induced bradycardia during acute sodium loading Am J Physiol Regulatory Integrative Comp Physiol, May 1, 2005; 288(5): R1211 - R1219. [Abstract] [Full Text] [PDF]

				V. L. Brooks, Y. Qi, and T. L. O'Donaughy Increased osmolality of conscious water-deprived rats supports arterial pressure and sympathetic activity via a brain action Am J Physiol Regulatory Integrative Comp Physiol, May 1, 2005; 288(5): R1248 - R1255. [Abstract] [Full Text] [PDF]

				V. L. Brooks, K. L. Freeman, and K. A. Clow Excitatory amino acids in rostral ventrolateral medulla support blood pressure during water deprivation in rats Am J Physiol Heart Circ Physiol, May 1, 2004; 286(5): H1642 - H1648. [Abstract] [Full Text] [PDF]

				S. D. Stocker, C. A. Smith, C. M. Kimbrough, E. M. Stricker, and A. F. Sved Elevated dietary salt suppresses renin secretion but not thirst evoked by arterial hypotension in rats Am J Physiol Regulatory Integrative Comp Physiol, June 1, 2003; 284(6): R1521 - R1528. [Abstract] [Full Text] [PDF]

				S. L. Bealer Increased dietary sodium alters neural control of blood pressure during intravenous ANG II infusion Am J Physiol Heart Circ Physiol, February 1, 2003; 284(2): H559 - H565. [Abstract] [Full Text] [PDF]