title: Marked sympathetic activation and baroreflex dysfunction in true resistant hypertension.
abstract: BACKGROUND
  An increase in sympathetic drive to the heart and the peripheral circulation characterizes mild and severe essential hypertension. However, it remains unsettled whether sympathetic cardiovascular influences are potentiated in true resistant hypertension (RHT).
  
  
  METHODS
  In 32 RHT patients treated with 4.6 ± 0.3 drugs (mean ± SEM) and aged 58.6 ± 2.1 years, 35 non-resistant treated hypertensives (HT) and 19 normotensive controls (NT), all age-matched with RHT, we measured clinic, 24-hour ambulatory and beat-to-beat blood pressures (BP), heart rate (HR, EKG), muscle sympathetic nerve traffic (MSNA, microneurography) and spontaneous baroreflex MSNA-sensitivity.
  
  
  RESULTS
  BP values were markedly greater in RHT patients than in NT and HT (172.2 ± 1.7/100.7 ± 1.2 vs 132.1 ± 1.3/82.1 ± 0.9 and 135.5 ± 1.2/83.6 ± 0.9 mmHg, P < 0.01). This was paralleled by a significant and marked increase in MSNA (87.8 ± 2.0 vs 46.8 ± 2.6 and 59.3 ± 1.7 and bursts/100 heartbeats, P < 0.01). In multiple regression analysis the MSNA increase observed in RHT was significantly related to hemodynamic, hormonal and metabolic variables. It was also significantly related to plasma aldosterone values as well as spontaneous baroreflex MSNA-sensitivity, which were the variables that at the multivariate analysis were more closely related to the adrenergic activation of RHT after adjustment for confounders, including antihypertensive treatment (r(2)partial=0.04405 and r(2)partial=0.00878, P<0.05 for both).
  
  
  CONCLUSIONS
  These data represent the first evidence that RHT is a state of marked adrenergic overdrive, greater for magnitude than that detectable in HT. They also suggest that impaired baroreflex mechanisms, along with hemodynamic and neurohumoral factors, may be responsible for the phenomenon.
authors.affiliation: Clinica Medica, Dipartimento di Medicina Clinica, Prevenzione e Biotecnologie Sanitarie, Universita Milano-Bicocca, Monza, Italy; IRCCS Multimedica, Sesto San Giovanni, Milano, Italy. Electronic address: guido.grassi@unimib.it.
authors.forename: Guido
authors.initials: G
authors.lastname: Grassi
authors.affiliation: Istituto Auxologico Italiano, Milano, Italy.
authors.forename: Gino
authors.initials: G
authors.lastname: Seravalle
authors.affiliation: Clinica Medica, Dipartimento di Medicina Clinica, Prevenzione e Biotecnologie Sanitarie, Universita Milano-Bicocca, Monza, Italy.
authors.forename: Gianmaria
authors.initials: G
authors.lastname: Brambilla
authors.affiliation: Dipartimento di Medicina, Ospedale S. Anna, Como, Italy.
authors.forename: Claudio
authors.initials: C
authors.lastname: Pini
authors.affiliation: Centro Cardiologico Monzino, Milano, Italy.
authors.forename: Marina
authors.initials: M
authors.lastname: Alimento
authors.affiliation: Clinica Medica, Dipartimento di Medicina Clinica, Prevenzione e Biotecnologie Sanitarie, Universita Milano-Bicocca, Monza, Italy.
authors.forename: Rita
authors.initials: R
authors.lastname: Facchetti
authors.affiliation: Unità Operativa di Cardiologia, Ospedale Magenta, Milano, Italy.
authors.forename: Domenico
authors.initials: D
authors.lastname: Spaziani
authors.affiliation: Clinica Medica, Dipartimento di Medicina Clinica, Prevenzione e Biotecnologie Sanitarie, Universita Milano-Bicocca, Monza, Italy; Istituto Auxologico Italiano, Milano, Italy.
authors.forename: Cesare
authors.initials: C
authors.lastname: Cuspidi
authors.affiliation: Istituto Auxologico Italiano, Milano, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Mancia
mesh_terms: D000328:Adult; D000368:Aged; D000959:Antihypertensive Agents / Q000494:pharmacology / Q000627:therapeutic use*; D017704:Baroreflex / Q000187:drug effects / Q000502:physiology*; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D000075222:Essential Hypertension; D005260:Female; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D006801:Humans; D006973:Hypertension / Q000175:diagnosis* / Q000188:drug therapy / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D013564:Sympathetic Nervous System / Q000503:physiopathology*
chemical_list: D000959:Antihypertensive Agents
keywords: Baroreceptors; Blood pressure; Nervous system; Reflex; Resistant hypertension