Effects of sodium intake on blood pressure and adrenergic vascular reactivity.
The effects of dietary sodium restriction (approximately 2 g daily) on blood pressure (BP) and vascular reactivity to norepinephrine (NE) were evaluated in 12 patients with uncomplicated primary hypertension. BP was significantly reduced at the end of the treatment both at rest (153/100 +/- 19/7 vs. 142/93 +/- 19/5 mmHg) and during an exercise test on a bicycle. The pressor response to NE was significantly lower at the end of the low sodium period (reactivity index = 0.0044 vs. 0.0031; p less than 0.05): A twofold dose of NE was needed to increase mean BP by 20 mmHg (PD20) (from 273 +/- 120 to 450 +/- 218 ng/kg/min; p less than 0.05). Twenty-four-hour NE excretion increased significantly on a low-salt diet (40 +/- 14 vs. 49 +/- 16 micrograms/24 hr; p less than 0.05). The decrease in BP was inversely related to changes in PD20 (R = -0.60; less than p0.05). These results provide the evidence that the fall in BP is, at least in part, mediated by decreased end-organ responsiveness to adrenergic stimulation.
D000328:Adult; D001794:Blood Pressure / Q000187:drug effects*; D001808:Blood Vessels / Q000187:drug effects*; D004039:Diet, Sodium-Restricted; D004305:Dose-Response Relationship, Drug; D005080:Exercise Test; D005260:Female; D006801:Humans; D006973:Hypertension / Q000178:diet therapy / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009638:Norepinephrine / Q000652:urine; D011941:Receptors, Adrenergic / Q000187:drug effects*; D012964:Sodium / Q000008:administration & dosage / Q000494:pharmacology*
D011941:Receptors, Adrenergic; D012964:Sodium; D009638:Norepinephrine