Key result
High-sodium diet (350 mmol/d) compared to low-sodium diet (10 mmol/d) in cardiac transplant recipients significantly increased systolic blood pressure (148 vs 137 mm Hg, P<0.05).
Why the study?
Does dietary sodium intake alter blood pressure and endocrine responses in cardiac transplant recipients compared to healthy and hypertensive controls?
RCT (n=36)
Double-blind
Does dietary sodium intake alter blood pressure and endocrine responses in cardiac transplant recipients compared to healthy and hypertensive controls?
p-value: p=< .05
Extensive cardiac denervation after transplantation does not prevent ANP responses to sodium intake, and blood pressure in these patients remains sensitive to sodium reduction.
Supports sodium restriction to lower BP in cardiac transplant recipients; extends evidence of sodium sensitivity despite denervation.
BACKGROUND: The role of cardiac extrinsic innervation in the regulation of sodium balance and blood pressure is controversial. METHODS AND RESULTS: We performed a double-blind study of endocrine and blood pressure responses to 5 days of low- (LS, 10 mmol/d) and 5 days of high- (350 mmol/d) sodium intake in 12 cardiac transplant recipients, 12 matched healthy subjects, and 12 matched subjects with untreated essential hypertension. In transplant recipients on low sodium, supine blood pressure was 137/94 +/- 8/4 (mean +/- SEM) mm Hg and plasma atrial natriuretic peptide (ANP) was 59.3 +/- 6.3 pg/mL; on high sodium, blood pressure was 148/97 +/- 5/3 mmHg (P < .05 for systolic pressure versus LS), and ANP was 94.3 +/- 10.6 pg/mL (P < .01 versus LS), respectively. Plasma ANP for those on each diet was significantly higher in the cardiac transplant recipients than in healthy or hypertensive controls; relative changes in plasma ANP in changing from low- to high-sodium diet were similar in each group. Urinary sodium excretion by the fifth day of each diet was similar in each group. Suppression of plasma renin activity and aldosterone by high-sodium diet was blunted in cardiac transplant recipients compared with healthy subjects (respectively, plasma renin activity: 1.41 +/- 0.30 versus 0.68 +/- 0.21 ng.mL-1 x h-1, P < .05; aldosterone: 391 +/- 35 versus 166 +/- 21 pmol/L, P < .05). CONCLUSIONS: These results suggest that extensive denervation of the heart does not result in major abnormalities in regulation of large changes in sodium intake and that intact cardiac innervation is not required for plasma ANP responses to altered sodium intake. Blood pressure after cardiac transplantation is sensitive to reduced sodium intake.
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Singer et al. (1994) conducted an RCT in Cardiac transplant recipients and essential hypertension (n=36). High-sodium diet vs. Low-sodium diet (10 mmol/d) was evaluated on Supine blood pressure and plasma atrial natriuretic peptide (ANP) (p=< .05). High-sodium diet (350 mmol/d) compared to low-sodium diet (10 mmol/d) in cardiac transplant recipients significantly increased systolic blood pressure (148 vs 137 mm Hg, P<0.05).
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