ELEVATED PLASMA AND URINARY ENDOTHELIN-1 LEVELS IN HUMAN SALT-SENSITIVE HYPERTENSION

1. The behaviour of the potent vasoconstrictive endothelium-derived pe ptide endothelin-1 was evaluated in salt-sensitive hypertension. 2. Ci rculating and urinary endothelin-1 levels were evaluated in 30 men (me an age 44.6+/-3.1 years) with uncomplicated essential hypertension aft er three consecutive 2-week periods on an intermediate (120 mmol), low (20 mmol) and high (240 mmol) NaCl diet, On the same occasions, blood pressure was measured to identify salt-sensitive patients (n = 16), i .e. those patients showing a mean blood pressure increase >10 mmHg whe n switching from a low to a high NaCl diet, and salt-resistant patient s (n = 14), i.e. those who did not show such mean blood-pressure varia tions. 3. Plasma endothelin-1 levels were higher (P<0.005) in salt-sen sitive than in salt-resistant hypertensive patients after intermediate -, low and high-NaCl diets, Urinary endothelin-1 excretion ws similar in both groups after an intermediate-NaCl diet, whereas it was signifi cantly higher in salt-sensitive than in salt-resistant hypertensive su bjects after low (P<0.002) and high (P<0.007) NaCl diets. High NaCl in take induced a significant increase in plasma endothelin-1 levels (P<0 .002) as compared with intermediate and low NaCl diet levels in salt-s ensitive patients, but did not in salt-resistant subjects. No signific ant NaCl intake-related variations of urinary endothelin-1 excretion w ere observed in either group. 4. Salt-sensitive hypertensives are char acterized by increased levels of endothelin-1 in both plasma and urine , This fact suggests that blood-pressure sensitivity to NaCl intake co uld be associated with an increased risk of developing both renal and cardiovascular damage.