title: Beta-adrenergic responsiveness is regulated selectively in hypertension.
abstract: beta-Adrenergic receptor responsiveness is impaired in hypertension. A low-sodium diet both corrects this defect and lowers blood pressure. To determine whether upregulation of beta-adrenergic receptor function in hypertension might be related nonspecifically to lowering of blood pressure, vascular beta-adrenergic response was assessed after pharmacologic antihypertensive treatment by use of dorsal hand vein linear differential transformer techniques in patients with hypertension. Subjects were studied after randomized treatments with placebo and verapamil and after randomized treatments with verapamil and hydrochlorothiazide. After 2 weeks of treatment, verapamil lowered blood pressure in the subjects with hypertension but did not significantly upregulate vascular beta-adrenergic response (58% +/- 8% to 68% +/- 8%; p > 0.2 versus placebo). Further vascular beta-adrenergic responsiveness after treatment with hydrochlorothiazide did not significantly differ from that with verapamil (hydrochlorothiazide, 68% +/- 9%; verapamil, 53% +/- 7%; n = 8, p > 0.3). Thus, reduction of blood pressure with either verapamil or hydrochlorothiazide did not correct the defect in beta-adrenergic responsiveness in hypertension. Vascular beta-adrenergic response appears to be regulated selectively in hypertension, not simply by lowering of blood pressure.
authors.affiliation: Department of Medicine, University of Western Ontario, London, Canada.
authors.forename: R D
authors.initials: RD
authors.lastname: Feldman
authors.forename: D J
authors.initials: DJ
authors.lastname: Freeman
authors.forename: G S
authors.initials: GS
authors.lastname: Bierbrier
authors.forename: S E
authors.initials: SE
authors.lastname: Anthony
authors.forename: J E
authors.initials: JE
authors.lastname: Brown
mesh_terms: D000328:Adult; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D004039:Diet, Sodium-Restricted; D006801:Humans; D006852:Hydrochlorothiazide / Q000494:pharmacology; D006973:Hypertension / Q000178:diet therapy / Q000188:drug therapy / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D010919:Placebos; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000502:physiology*; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology*; D014700:Verapamil / Q000494:pharmacology
chemical_list: D010919:Placebos; D011943:Receptors, Adrenergic, beta; D006852:Hydrochlorothiazide; D014700:Verapamil