Key result
Hypertensive patients with reduced GFR had significantly elevated upright plasma norepinephrine compared to healthy controls (4.4 vs 2.1 nmol/l; P<0.001).
Why the study?
Does upright body position affect plasma norepinephrine and ANP levels in hypertensive patients with chronic renal failure compared to healthy controls?
Cross-Sectional (n=20)
Does upright body position affect plasma norepinephrine and ANP levels in hypertensive patients with chronic renal failure compared to healthy controls?
Absolute Event Rate: 4.4% vs 2.1%
p-value: p=<0.001
Hypertensive patients with chronic renal failure exhibit elevated plasma norepinephrine and ANP levels in the upright position, suggesting position-dependent sympathetic overactivity.
May indicate position-dependent sympathetic overactivity in renal hypertension; leaves open causal role and need for prospective trials.
OBJECTIVE: The renal functional consequences of an activated sympathetic nervous system and plasma atrial natriuretic hormone (ANP) in various renal diseases are not well described. We hypothesize that norepinephrine (NE) and ANP have antagonizing effects on renal hemodynamics in diseased kidneys. MATERIAL AND METHODS: Plasma NE, ANP. glomerular filtration rate (GFR), effective renal plasma flow (ERPF) and mean arterial pressure (MAP) were measured in the upright position in healthy controls (n = 9) and hypertensive patients with reduced GFR (n =11). The same parameters were compared between healthy controls (n = 6) and hypertensive patients with reduced GFR (n = 6) in upright and supine positions. RESULTS: Upright plasma NE and ANP were significantly elevated in the patients compared with the controls (4.4 +/- 0.4 vs 2.1 +/- 0.2 nmol/l (p < 0.001) and 1.3.5 +/- 2.1 vs 6.9 +/- 1.0 nmol/l (p < 0.01) respectively). With change from upright to supine position plasma NE decreased in the controls (2.2 +/- 0.3 vs 1.7 +/- 0.3 nmol/l) (p < 0.01) and patients (3.8 +/- 0.4 vs 2.6 +/- 0.4) (p < 0.01). Supine ANP increased in controls (5.5 +/- 1.0 vs 8.3 +/- 1.1) (p < 0.01) but not in patients (14.3 +/- 3.8 vs 16.1 +/- 3.8 nmol/l) (p > 0.10). Plasma NE correlated positively with MAP (p < 0.001) and negatively with GFR (p < 0.01) in the upright but not supine position. A positive correlation between NE and ANP was observed in upright (p < 0.001) but not in supine position. ANP correlated negatively with GFR in the upright (p < 0.01) but not supine position. No position dependent changes were seen in GFR and ERPF, but supine filtration fraction (FF) increased insignificantly in the patient group (0.23 +/- 0.02 vs 0.24 +/- 0.02) (p < 0.05). CONCLUSION: Hypertensive patients with reduced GFR have elevated levels of plasma NE and ANP in the upright body position. When the upright and supine positions are compared, plasma NE declines in the supine position in controls and hypertensive renal failure patients. and plasma ANP levels are elevated only in the upright position in hypertensive renal failure patients where the sympathetic nervous system is activated. A significant positive relationship between plasma NE and ANP was observed only in the upright position. The upright body position seems superior to recumbency in the characterization of these hormonal changes in hypertensive chronic renal failure patients.
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O. Myking E. Svarstad (2001) conducted a cross-sectional in Hypertension with chronic renal failure (n=20). Hypertension with reduced GFR vs. Healthy controls was evaluated on Upright plasma norepinephrine (NE) levels (nmol/l) (p=<0.001). Hypertensive patients with reduced GFR had significantly elevated upright plasma norepinephrine compared to healthy controls (4.4 vs 2.1 nmol/l; P<0.001).
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