Increased plasma norepinephrine in young patients with essential hypertension under three sodium intakes.

Abstract

SUMMARY Increased sympathetic nerve activity may play an important role in the pathogenesis of essential hypertension. It is well known that both dietary sodium intake and age influence the plasma norepinephrine (NE) concentration. The present study was undertaken to evaluate the effects of age on sympathetic nerve activity in patients with essential hypertension and normal control subjects under low-, regular-, and high-sodium regimens (mean 24-hour sodium excretions: 30 ± 4,116 ± 7, 280 ± 15 mEq, respectively). Plasma NE and eplnephrine (E) were analyzed by trihydroxyindole methods after high-performance liquid chromatography separation. Subjects were categorized by age into young (^40 yrs), middle-aged (40-60 years), and old (>60 years) subgroups. Mean plasma NE in hypertensive patients was significantly higher (p < 0.01) than in normal subjects on each of the sodium regimens. In normal control subjects, there was a significant positive correlation between age and plasma NE with all three sodium intakes. However, no correlation was seen in hypertensive patients on any of the sodium regimens, because in the young subgroup of hypertensive patients the mean plasma NE was significantly higher than that of normal control subjects. These results suggest that the increased sympathetic nerve activity plays an important role in the pathogenesis of essential hypertension, especially in young patients. (Hypertension 6: 315-321, 1984) KEY WORDS • essential hypertension urinary sodium excretion age • plasma norepinephrine M ANY studies have focused on the involvement of the sympathetic nervous system in the pathogenesis and development of essential hypertension.13 However, the findings remain controversial.4 " 6 Some investigators 7 -8 have reported increased levels of plasma norepinephrine (NE) and increased excretion of urinary NE in patients with essential hypertension. Others workers 9 "" have reported no change or decrease in these factors. Reports on the relationship between age and plasma NE are also inconsistent. Some investigators have shown an elevation of plasma NE with aging in normal subjects, and/ or patients with essential hypertension. 9101213 It is also well known that the amount of sodium intake influences plasma NE levels.'*~17 There are few studies on the relationship between age and plasma NE in normal subjects and patients with essential hypertension under various sodium intakes.From the Department of Medicine and Geriatrics (Drs. Masuo, Ogihara, and Kumahara) and the Second Department of Pharmacology (Drs. Yamatodani and Wada), Osaka University Medical School, Osaka, Japan.Address for reprints: Toshio Ogihara, M.D., Department of Medicine and Geriatrics, Osaka University Medical School, Fukushima-ku, Osaka 553, Japan.Received April 4, 1983; revision accepted October 3, 1983.In this study, we evaluated the influence of age on plasma NE and epinephrine (E) in both normal subjects and patients with essential hypertension under low-, regular-, and high-sodium intake. Materials and Methods SubjectsFo...

Orthostatic and Postprandial Blood Pressure Reduction in Patients With Essential Hypertension

“…There are many reports on comparisons of plasma NE in hypertensive and normotensive subjects at rest and during exercise or standing, but the results have not been conclusive. Plasma NE levels are influenced by the levels of sodium intake, age, and a family history of hypertension (Christensen & Brandsborg 1973;McDermott et al 1974;Masuo et al 1983Masuo et al , 1984Munger et al 1986). In the present study, therefore, we compared plasma NE levels at rest, on standing and after a certain amount of liquid meal, between male hypertensive and normotensive subjects of similar age with similar dietary intakes of sodium and potassium.…”

Age-related changes in blood pressure.

“…A decreasing ability with age to handle exogenous blood pressure-affecting factors such as salt intake, extracellular volume, and serum proteins may also be of importance. 22 Several previous studies 23 " 29 have investigated possible age-related changes in the production of catecholamines. The results are conflicting, but the majority of these studies conclude that increased norepinephrine levels are balanced by a decrease in receptor sensitivity.…”

Hormonal Mechanisms in Blood Pressure Reduction during Hemodialysis in Patients with Chronic Renal Failure

“…Some investigators (2,3) have also reported that plasma NE clearance was increased in renal failure. However, it is also known that plasma NE, as an index of sympathetic nerve activity, increases with aging (4) and that plasma NE responses to change is position is increased (5,6).…”