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: 292/4/R1675    most recent 00623.2006v1 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 (5) Citing Articles via Google Scholar Google Scholar Articles by Freeman, K. L. Articles by Brooks, V. L. Search for Related Content PubMed PubMed Citation Articles by Freeman, K. L. Articles by Brooks, V. L.

WATER AND ELECTROLYTE HOMEOSTASIS

AT₁ and glutamatergic receptors in paraventricular nucleus support blood pressure during water deprivation

Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, Oregon

Submitted 31 August 2006 ; accepted in final form 20 December 2006

Water deprivation activates sympathoexcitatory neurons in the paraventricular nucleus (PVN); however, the neurotransmitters that mediate this activation are unknown. To test the hypothesis that ANG II and glutamate are involved, effects on blood pressure (BP) of bilateral PVN microinjections of ANG II type 1 receptor (AT1R) antagonists, candesartan and valsartan, or the ionotropic glutamate receptor antagonist, kynurenate, were determined in urethane-anesthetized water-deprived and water-replete male rats. Because PVN may activate sympathetic neurons via the rostral ventrolateral medulla (RVLM) and because PVN disinhibition increases sympathetic activity in part via increased drive of AT1R in the RVLM, candesartan was also bilaterally microinjected into the RVLM. Total blockade of the PVN with bilateral microinjections of muscimol, a GABA_A agonist, decreased BP more (P < 0.05) in water-deprived (–29 ± 8 mmHg) than in water-replete (–7 ± 2 mmHg) rats, verifying that the PVN is required for BP maintenance during water deprivation. PVN candesartan slowly lowered BP by 7 ± 1 mmHg (P < 0.05). In water-replete rats, however, candesartan did not alter BP (1 ± 1 mmHg). Valsartan also produced a slowly developing decrease in arterial pressure (–6 ± 1 mmHg; P < 0.05) in water-deprived but not in water-replete (–1 ± 1 mmHg) rats. In water-deprived rats, PVN kynurenate rapidly decreased BP (–19 ± 3 mmHg), and the response was greater (P < 0.05) than in water-replete rats (–4 ± 1 mmHg). Finally, as in PVN, candesartan in RVLM slowly decreased BP in water-deprived (–8 ± 1 mmHg; P < 0.05) but not in water-replete (–3 ± 1 mmHg) rats. These data suggest that activation of AT₁ and glutamate receptors in PVN, as well as of AT1R in RVLM, contributes to BP maintenance during water deprivation.

angiotensin II; rostral ventrolateral medulla; candesartan; valsartan; glutamate

This article has been cited by other articles:

				R. Frithiof, R. Ramchandra, S. Hood, C. May, and M. Rundgren Hypothalamic paraventricular nucleus mediates sodium-induced changes in cardiovascular and renal function in conscious sheep Am J Physiol Regulatory Integrative Comp Physiol, July 1, 2009; 297(1): R185 - R193. [Abstract] [Full Text] [PDF]

				F. Chen, M. Dworak, Y. Wang, J. L. Cham, and E. Badoer Role of the hypothalamic PVN in the reflex reduction in mesenteric blood flow elicited by hyperthermia Am J Physiol Regulatory Integrative Comp Physiol, December 1, 2008; 295(6): R1874 - R1881. [Abstract] [Full Text] [PDF]

				J. M. Adams, J. J. McCarthy, and S. D. Stocker Excess Dietary Salt Alters Angiotensinergic Regulation of Neurons in the Rostral Ventrolateral Medulla Hypertension, November 1, 2008; 52(5): 932 - 937. [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]