Mild chronic renal insufficiency induces sympathetic overactivity

• Published in: Journal of human hypertension Vol. 15; no. 6; pp. 401 - 406
• Main Authors: TINUCCI, T, ABRAHAO, S. B, SANTELLO, J. L, MION, D. JR
• Format: Journal Article
• Language: English
• Published: Basingstoke Nature Publishing 01-06-2001; Nature Publishing Group
• Subjects: Adult; Antihypertensive Agents - pharmacology; Arterial hypertension. Arterial hypotension; Baroreceptors; Biological and medical sciences; Blood and lymphatic vessels; Blood pressure; Blood Pressure - drug effects; Cardiology. Vascular system; Clinical manifestations. Epidemiology. Investigative techniques. Etiology; Creatinine - blood; Female; Humans; Hypertension - complications; Kidney Failure, Chronic - complications; Least-Squares Analysis; Linear Models; Male; Medical sciences; Middle Aged; Neck; Nitroprusside - pharmacology; Peroneal nerve; Phenylephrine; Phenylephrine - pharmacology; Reflexes; Renal function; Renal insufficiency; Renin - blood; Sodium nitroprusside; Sympathetic nerves; Sympathetic Nervous System - drug effects; Sympathetic Nervous System - physiopathology; Tropical medicine; Vasoconstrictor Agents - pharmacology; Kidney disease; Human; Hypertension; Chronic; Urinary system disease; Pathophysiology; Renal failure; Cardiovascular disease; Complication; Exploration; Sympathetic nervous system; Comparative study
• ISSN: 0950-9240; 1476-5527
• DOI: 10.1038/sj.jhh.1001149

The objectives of this study were to evaluate baseline sympathetic nerve activity as well as the mechanisms of sympathetic overactivity in mild chronic renal insufficiency hypertension. Seven hypertensives with mild renal insufficiency, seven hypertensives with normal renal function and seven normotensives, age and weight-matched were studied on one session to evaluate baseline muscle sympathetic nerve activity measured in the peroneal nerve. The mild renal insufficiency hypertensives and the hypertensives with normal renal function were also studied to evaluate arterial baroreflex control of muscle sympathetic nerve activity assessed by increasing and decreasing blood pressure through continuous infusion of phenylephrine and sodium nitroprusside respectively. Baseline muscle sympathetic nerve activity was significantly higher in mild renal insufficiency hypertensives (34 bursts/min) when compared to hypertensives with normal renal function (24 bursts/min) and to normotensives (16 bursts/min). Baroreflex control of muscle sympathetic nerve activity was (in absolute values) 15.2 in hypertensives with normal renal function vs 2.6 in mild renal insufficiency hypertensives (P < 0.05) during phenylephrine and 6.3 vs 8.2 during nitroprusside infusions. Mild renal insufficiency hypertensives showed sympathetic overactivity when compared to hypertensives with normal renal function and to normotensives. This finding demonstrates that elevated sympathetic activity may be precociously detected in renal insufficiency. Baroreflex gain to phenylephrine was blunted in mild renal insufficiency hypertensives when compared to hypertensives with normal renal function, suggesting that bradycardic response in mild renal insufficiency is blunted.