Relation of blood pressure and body sodium content during sodium depletion in normal and hypertensive subjects.
Blood pressure, exchangeable sodium content, sodium metabolic balance, and plasma concentrations of active renin, angiotensin II, and aldosterone were measured in seven normal men and 10 essential hypertensive men of similar age and weight. The measurements were made under two circumstances: during a 2- to 3-day period of normal sodium intake of 145-150 mmol/24 h and during a 2- to 3-day period of sodium depletion produced by 40 mg frusemide and a dietary sodium intake less than 10 mmol/24 h. Mean arterial pressure decreased in nine of the 10 hypertensive subjects but increased in six of the seven normotensive subjects during sodium depletion. Blood pressure changed more for a given change in exchangeable sodium level in hypertensive subjects than in normotensive subjects, despite a similar loss of sodium in the two groups. Changes in blood pressure varied markedly in the hypertensive group. Patients showing the greatest fall in arterial pressure had the least rise in plasma active renin concentration and, not significantly, the least rise in plasma aldosterone level. These findings are compatible with a model of pressure natriuresis which is altered more in normal subjects during changes in dietary sodium content, thereby preventing a rise in arterial pressure. Failure of this compensatory mechanism in hypertensive subjects may raise blood pressure.
D000328:Adult; D000450:Aldosterone / Q000097:blood; D000804:Angiotensin II / Q000097:blood; D001794:Blood Pressure; D004039:Diet, Sodium-Restricted; D004232:Diuretics / Q000494:pharmacology; D006801:Humans; D006973:Hypertension / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D012083:Renin / Q000097:blood; D012964:Sodium / Q000008:administration & dosage / Q000378:metabolism*
D004232:Diuretics; D000804:Angiotensin II; D000450:Aldosterone; D012964:Sodium; D012083:Renin