title: The influence of antihypertensive therapy on the structural arteriolar changes in essential hypertension: different effects of enalapril and hydrochlorothiazide.
abstract: OBJECTIVE
  To assess the peripheral and central haemodynamics, in particular the effect on minimal resistance in the hand, with an ACE inhibitor in comparison with a diuretic.
  
  
  METHODS
  Double-blind randomized parallel group study.
  
  
  METHODS
  Twenty-eight previously untreated men with essential hypertension (supine diastolic blood pressure > 95 mmHg repeatedly on placebo). METHODS/INTERVENTION: Causal and intra-arterial blood pressure, dye-dilution technique, water plethysmography at rest and at ischaemia, enalapril (n = 14), hydrochlorothiazide (n = 14).
  
  
  RESULTS
  After 6 months the mean arterial pressure was reduced from 112.7 to 96.9 mmHg (change -15.9 mmHg; 95% confidence interval (CI) -21.9, -9.8) on enalapril and from 110.1 to 101.5 mmHg (change -8.6 mmHg; CI -14.4, -2.8). Heart rate did not change on any of the therapies. Enalapril reduced blood pressure mainly through a reduction in total peripheral resistance (delta -3.0 PRU100; CI -5.6, -0.4) while hydrochlorothiazide reduced blood pressure mainly through a reduction in cardiac output (delta -0.8 l/min-1; CI -1.5, -0.07). Minimal vascular resistance (mean of right and left hand) displayed a significant time x treatment interaction indicating a different trend with enalapril than hydrochlorothiazide with a change of -0.12 PRU100 (CI -0.33, 0.05) on enalapril and a change of 0.14 (CI -0.29, 0.56) on hydrochlorothiazide. The resistance level after 6 months was significantly higher on hydrochlorothiazide than on enalapril (P = 0.0105).
  
  
  CONCLUSIONS
  Enalapril reduced blood pressure through vasodilatation and hydrochlorothiazide through decreased cardiac output. The two therapies also affected minimal vascular resistance (an indirect measure of vascular wall thickness) differently; with enalapril showing a favourable response in contrast to hydrochlorothiazide.
authors.affiliation: Department of Medicine, University of Göteborg, Ostra Hospital, Sweden.
authors.forename: B
authors.initials: B
authors.lastname: Dahlöf
authors.forename: L
authors.initials: L
authors.lastname: Hansson
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001160:Arterioles / Q000187:drug effects*; D002302:Cardiac Output / Q000187:drug effects; D004311:Double-Blind Method; D004656:Enalapril / Q000494:pharmacology* / Q000627:therapeutic use; D006225:Hand / Q000098:blood supply; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D006852:Hydrochlorothiazide / Q000494:pharmacology* / Q000627:therapeutic use; D006973:Hypertension / Q000188:drug therapy* / Q000473:pathology* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D014655:Vascular Resistance / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects
chemical_list: D006852:Hydrochlorothiazide; D004656:Enalapril