title: The effect of sodium depletion on plasma norepinephrine kinetics in patients with essential hypertension.
abstract: The effects of sodium depletion on plasma norepinephrine (NE) kinetics were studied in 14 patients with essential hypertension using the steady state NE infusion technique on the theoretical basis of a two-compartmental open model. The calculated half time of rapid removal phase (t 1/2 alpha) of plasma NE was significantly delayed in the hypertensives (1.20 +/- 0.22 min, mean +/- SD) than in normal subjects (0.89 +/- 0.14) (p less than 0.01). The total clearance rates were comparable between the 2 groups (47 +/- 7 vs 48 +/- 11 ml/kg/min). The rates of the endogenous NE outflow into the circulation (RE-NE) were not significantly different between normal (5.29 +/- 1.68 ng/kg/min) and hypertensives (7.69 +/- 5.42), although 5 hypertensive patients (36%) showed an increased RE-NE above the normal range. The prolonged half time (t 1/2 alpha) in the hypertensives tended to be shortened after sodium depletion induced by either low sodium diet or diuretics (1.04 +/- 0.22, p less than 0.001). Both plasma NE and RE-NE were significantly increased after sodium depletion. A close correlation was observed between plasma NE and RE-NE (r = 0.907, p less than 0.001) in these subjects. These results suggest the slowed neuronal uptake of NE at the sympathetic nerve terminals in some patients with essential hypertension, occurring in part as a sodium-mediated consequence.
mesh_terms: D000293:Adolescent; D000328:Adult; D001794:Blood Pressure; D005260:Female; D006339:Heart Rate; D006801:Humans; D006973:Hypertension / Q000097:blood / Q000378:metabolism* / Q000503:physiopathology; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D009638:Norepinephrine / Q000097:blood*; D012964:Sodium / Q000378:metabolism*; D014655:Vascular Resistance
chemical_list: D012964:Sodium; D009638:Norepinephrine