title: Adrenergic, metabolic, and reflex abnormalities in reverse and extreme dipper hypertensives.
abstract: Limited information is available on whether and to what extent the different patterns of the nocturnal blood pressure profile reported in hypertension are characterized by differences in sympathetic drive that may relate to, and account for, the different day-night blood pressure changes. In 34 untreated middle-aged essential hypertensive dippers, 17 extreme dippers, 18 nondippers, and 10 reverse dippers, we assessed muscle sympathetic nerve traffic, heart rate, and beat-to-beat arterial blood pressure at rest and during baroreceptor deactivation and stimulation. Measurements were also performed in 17 age-matched dipper normotensives. All patients displayed reproducible blood pressure patterns at 2 different monitoring sessions. The 4 hypertensive groups did not differ by gender or 24-hour or daytime blood pressure. Muscle sympathetic nerve traffic was significantly higher in nondipper, dipper, and extreme dipper hypertensives than in normotensive controls (58.6+/-1.8, 55.6+/-0.9, and 53.3+/-0.8 versus 43.5+/-1.4 bursts/100 heartbeats, respectively; P<0.01 for all), a further significant increase being detected in reverse dippers (76.8+/-3.1 bursts/100 heartbeats; P<0.05). Compared with normotensives, baroreflex-heart rate control was similarly impaired in all the 4 hypertensive states, whereas baroreflex-sympathetic control was preserved. The day-night blood pressure difference correlated inversely with sympathetic nerve traffic (r=-0.76; P<0.0001) and homeostasis model assessment index (r=-0.32; P<0.005). Thus, the reverse dipping state is characterized by a sympathetic activation greater for magnitude than that seen in the other conditions displaying abnormalities in nighttime blood pressure pattern. The present data suggest that in hypertension, sympathetic activation represents a mechanism potentially responsible for the day-night blood pressure difference.
authors.affiliation: Dipartimento di Medicina Clinica, Clinica Medica, Prevenzione e Biotecnologie Sanitarie, Università Milano-Bicocca, Ospedale San Gerardo, Monza, Italy. guido.grassi@unimib.it
authors.forename: Guido
authors.initials: G
authors.lastname: Grassi
authors.forename: Gino
authors.initials: G
authors.lastname: Seravalle
authors.forename: Fosca
authors.initials: F
authors.lastname: Quarti-Trevano
authors.forename: Raffaella
authors.initials: R
authors.lastname: Dell'Oro
authors.forename: Michele
authors.initials: M
authors.lastname: Bombelli
authors.forename: Cesare
authors.initials: C
authors.lastname: Cuspidi
authors.forename: Rita
authors.initials: R
authors.lastname: Facchetti
authors.forename: Gianbattista
authors.initials: G
authors.lastname: Bolla
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Mancia
mesh_terms: D000320:Adrenergic Fibers / Q000502:physiology*; D000328:Adult; D017704:Baroreflex / Q000502:physiology*; D001786:Blood Glucose / Q000378:metabolism; D001794:Blood Pressure / Q000502:physiology; D018660:Blood Pressure Monitoring, Ambulatory; D015992:Body Mass Index; D016022:Case-Control Studies; D002784:Cholesterol / Q000097:blood; D002940:Circadian Rhythm / Q000502:physiology*; D003404:Creatinine / Q000097:blood; D005260:Female; D006801:Humans; D006973:Hypertension / Q000503:physiopathology*; D007328:Insulin / Q000097:blood; D008297:Male; D008875:Middle Aged; D013564:Sympathetic Nervous System / Q000502:physiology*
chemical_list: D001786:Blood Glucose; D007328:Insulin; D002784:Cholesterol; D003404:Creatinine