The aim of the present study was to investigate whether plasma concentration of proANP 1-30 , the N-terminal fragment of the atrial natriuretic peptide prohormone, or 24-hour urinary excretion of urodilatin reflects the degree of salt sensitivity in hypertension-prone individuals. Plasma concentration of proANP 1-30 and urinary urodilatin excretion were determined at baseline, after 1 week on a low-salt diet (10 mmol/d) and after another week on a high-salt diet (240 mmol/d) in 30 healthy

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... ts with heredity for hypertension. Salt sensitivity was defined as the difference between mean arterial blood pressure after the high-salt diet and the mean arterial blood pressure after the low-salt diet. High-versus low-salt intake increased proANP 1-30 (668Ϯ330 versus 358Ϯ150 pmol/L; PϽ0.00001) and urodilatin (18.7Ϯ5.2 versus 16.0Ϯ8.3 pmol/24 h; PϽ0.05). ProANP 1-30 correlated with salt sensitivity at baseline (rϭ0.76, PϽ0.000001), after the low-(rϭ0.80, PϽ0.0000001) and high-salt diets (rϭ0.85, PϽ0.00000001). The increase in proANP 1-30 induced by changing from the low-to the high-salt diet was also directly related to salt sensitivity (rϭ0.78, PϽ0.000001). ProANP 1-30 was not related to urinary sodium excretion. Neither urodilatin nor the sodium-induced change in urodilatin correlated with salt sensitivity. However, urodilatin was related to the urinary sodium excretion at baseline (rϭ0.58, PϽ0.01) and after the high-salt diet (rϭ0.62, PϽ0.001). In conclusion, the close correlations between proANP 1-30 and salt sensitivity suggest that proANP 1-30 may serve as a marker for salt sensitivity and could be useful in identifying subjects who would benefit from dietary salt restriction to prevent development of hypertension. (Hypertension. 2002;39:996-999.)