title: Sodium intake influences hemodynamic and neural responses to angiotensin receptor blockade in rostral ventrolateral medulla.
abstract: To determine the effects of physiological alterations in endogenous angiotensin II activity on basal renal sympathetic nerve activity (RSNA) and its arterial baroreflex regulation, angiotensin II type 1 receptor antagonists were microinjected into the rostral ventrolateral medulla of anesthetized rats consuming a low, normal, or high sodium diet that were instrumented for simultaneous measurement of arterial pressure and RSNA. Plasma renin activity was increased in rats fed a low sodium diet and decreased in those fed a high sodium diet. Losartan (50, 100, and 200 pmol) decreased heart rate and RSNA (but not mean arterial pressure) dose-dependently; the responses were significantly greater in rats fed a low sodium diet than in those fed a high sodium diet. Candesartan (1, 2, and 10 pmol) decreased mean arterial pressure, heart rate, and RSNA dose-dependently; the responses were significantly greater in rats fed a low sodium diet than in those fed a normal or high sodium diet. [D-Ala(7)]Angiotensin-(1-7) (100, 200, and 1000 pmol) did not affect mean arterial pressure, heart rate, or RSNA in rats fed either a low or a high sodium diet. In rats fed a low sodium diet, candesartan reset the arterial baroreflex control of RSNA to a lower level of arterial pressure, and in rats with congestive heart failure, candesartan increased the arterial baroreflex gain of RSNA. Physiological alterations in the endogenous activity of the renin-angiotensin system influence the bradycardic, vasodepressor, and renal sympathoinhibitory responses to rostral ventrolateral medulla injection of antagonists to angiotensin II type 1 receptors but not to angiotensin-(1-7) receptors.
authors: Department of Internal Medicine, University of Iowa College of Medicine, and Veterans Administration Medical Center, Iowa City, Iowa 52242, USA.
authors: G F
authors: GF
authors: DiBona
authors: S Y
authors: SY
authors: Jones
mesh_terms: D000803:Angiotensin I / Q000494:pharmacology; D057911:Angiotensin Receptor Antagonists; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology; D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology; D017704:Baroreflex / Q000502:physiology*; D001562:Benzimidazoles / Q000494:pharmacology; D001713:Biphenyl Compounds; D001794:Blood Pressure / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D006333:Heart Failure / Q000503:physiopathology; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D007668:Kidney / Q000294:innervation* / Q000502:physiology; D019808:Losartan / Q000494:pharmacology; D008297:Male; D008526:Medulla Oblongata / Q000187:drug effects; D008845:Microinjections; D010446:Peptide Fragments / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011945:Receptors, Angiotensin / Q000378:metabolism*; D012083:Renin / Q000097:blood; D012084:Renin-Angiotensin System / Q000502:physiology; D012982:Sodium, Dietary / Q000008:administration & dosage*; D013564:Sympathetic Nervous System / Q000378:metabolism*; D013777:Tetrazoles / Q000494:pharmacology
chemical_list: D057911:Angiotensin Receptor Antagonists; D000806:Angiotensin-Converting Enzyme Inhibitors; D000959:Antihypertensive Agents; D001562:Benzimidazoles; D001713:Biphenyl Compounds; D010446:Peptide Fragments; D011945:Receptors, Angiotensin; D012982:Sodium, Dietary; D013777:Tetrazoles; D000803:Angiotensin I; D012083:Renin; C118790:angiotensin I (1-7); D019808:Losartan; C081643:candesartan