title: The effects of acute and chronic dihydropyridine calcium antagonist therapy on baroreflex sensitivity: a re-analysis using the sequence method.
abstract: The objective of this study was to examine the effects of dihydropyridine calcium antagonist therapy on 24-h baroreflex sensitivity. Twenty-three patients with moderate essential hypertension were studied before and during acute (10 patients) and chronic (21 patients) treatment with a dihydropyridine calcium antagonist (nifedipine, nicardipine or felodipine) as monotherapy in a dose titrated to produce a fall in mean cuff pressure of at least 10%. Twenty-four hour unrestricted ambulatory intra-arterial blood pressure (IABP) and heart rate (R-R interval) were monitored. Baroreflex sensitivity (BRS) was assessed throughout the 24-h period by off-line computer analysis of spontaneous variations in IABP and R-R interval. During acute first dose treatment with a calcium antagonist there was a significant fall in blood pressure (BP), increase in heart rate and reduction in BRS. With chronic therapy (6-16 weeks) there was a continued reduction in mean BP of 11% (P < 0.001), but heart rate had returned to control levels and BRS was significantly increased over the 24 h by 14% (P < 0.01). The increase in BRS was evident during both the waking and sleeping periods, but the greatest increase was during sleep (awake 12% P = 0. 02, asleep 28% P = 0.003). In conclusion, although dihydropyridine calcium antagonists acutely cause a reflex tachycardia associated with a reduced BRS, there is no such effect with chronic therapy. BRS was significantly increased after chronic treatment, with exaggeration of the diurnal pattern. Journal of Human Hypertension (2000) 14, 189-194.
authors.affiliation: Department of Cardiovascular Medicine, Queen Elizabeth Hospital, Edgbaston, Birmingham B15 2TH, UK.
authors.forename: J C
authors.initials: JC
authors.lastname: Vaile
authors.forename: P J
authors.initials: PJ
authors.lastname: Jordan
authors.forename: T J
authors.initials: TJ
authors.lastname: Stallard
authors.forename: W A
authors.initials: WA
authors.lastname: Littler
mesh_terms: D000328:Adult; D017704:Baroreflex / Q000187:drug effects*; D001794:Blood Pressure / Q000187:drug effects; D018660:Blood Pressure Monitoring, Ambulatory; D002121:Calcium Channel Blockers / Q000627:therapeutic use*; D002309:Cardiology / Q000379:methods; D015736:Felodipine / Q000627:therapeutic use*; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D006973:Hypertension / Q000188:drug therapy* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009529:Nicardipine / Q000627:therapeutic use*; D013997:Time Factors
chemical_list: D002121:Calcium Channel Blockers; D009529:Nicardipine; D015736:Felodipine