[Does dopamine play a role in renal anomaly in sodium excretion, a marker for hereditary predisposition to arterial hypertension?].

Since Dahl's observation, a renal defect os sodium excretion is proposed as one of pathogenetic mechanism of hypertension (HTA). Our study has tried to verify this concept in 20 young normotensives with (n = 12) and without (n = 8) familial predisposition to HTA, allowing to test the genetic transmission of such potential renal abnormality of sodium balance. Each people was submitted to 3 different Na diet (20, 170 and 340 mM NaCl) each for 1 week. At each visit, blood pressure, vascular resistances, biological values were determined at rest (plasma renin activity, creatinine clearance, 24 hours before the test, catecholamines, aldosterone and ion urinary excretion). Then 1 liter of isotonic saline was perfused in 30 minutes with measures of blood pressure and 3 hours urinary dopamine and Na excretion. During the low and medium Na diets, but not during the high Na diet, the natriuresis and dopamine excretion were lower in the 3 hour urine collection in patients with a family history of HTA (p less than 0.02 and p less than 0.005, respectively). No other clinical or biological difference was noted between the 2 groups. Thus, genetic hypertensive predisposition seems to be characterized by a lower Na excretion during acute Na loading in normal or depleted Na diet, linked to an impaired urinary dopamine excretion. These findings suggest that the defect responsible for the susceptibility to sodium intake is at the kidney level. Some dopamine agonists would be of great therapeutical value in treating such patients when blood pressure begins to rise.