title: Effect of endogenous angiotensin II on renal nerve activity and its cardiac baroreflex regulation.
abstract: The effects of physiologic alterations in endogenous angiotensin II activity on basal renal sympathetic nerve activity and its cardiac baroreflex regulation were studied. The effect of angiotensin II type 1 receptor blockade with intracerebroventricular losartan was examined in conscious rats consuming a low, normal, or high sodium diet that were instrumented for the simultaneous measurement of right atrial pressure and renal sympathetic nerve activity. The gain of cardiac baroreflex regulation of renal sympathetic nerve activity (% delta renal sympathetic nerve activity/mmHg mean right atrial pressure) was measured during isotonic saline volume loading. Intracerebroventricular losartan did not decrease arterial pressure but significantly decreased renal sympathetic nerve activity in low (-36+/-6%) and normal (-24+/-5%), but not in high (-2+/-3%) sodium diet rats. Compared with vehicle treatment, losartan treatment significantly increased cardiac baroreflex gain in low (-3.45+/-0.20 versus -2.89+/-0.17) and normal (-2.89+/-0.18 versus -2.54+/-0.14), but not in high (-2.27+/-0.15 versus -2.22+/-0.14) sodium diet rats. These results indicate that physiologic alterations in endogenous angiotensin II activity tonically influence basal levels of renal sympathetic nerve activity and its cardiac baroreflex regulation.
authors.affiliation: Department of Internal Medicine, University of Iowa College of Medicine, and Department of Veterans Affairs Medical Center, Iowa City 52252, USA.
authors.forename: G F
authors.initials: GF
authors.lastname: Dibona
authors.forename: S Y
authors.initials: SY
authors.lastname: Jones
authors.forename: L L
authors.initials: LL
authors.lastname: Sawin
mesh_terms: D000804:Angiotensin II / Q000502:physiology*; D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology; D017704:Baroreflex / Q000502:physiology*; D001794:Blood Pressure / Q000187:drug effects; D004039:Diet, Sodium-Restricted; D006321:Heart / Q000502:physiology*; D006339:Heart Rate / Q000187:drug effects; D007276:Injections, Intraventricular; D007668:Kidney / Q000294:innervation*; D019808:Losartan / Q000494:pharmacology; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000502:physiology*
chemical_list: D000959:Antihypertensive Agents; D000804:Angiotensin II; D019808:Losartan