Jean-Louis Cuche

Autonomic Nervous System and Benign Essential Hypertension in Man

The clinical entity of benign essential hypertension is often subdivided into labile essential hypertension and stable essential hypertension. To establish less arbitrary limits between normotension and labile and stable benign essential hypertension, 70 subjects (56 with benign essential hypertension) were classified according to (a) the usual blood pressure index for each subject and (b) the upper limit of variation of the usual blood pressure indexes of a normotensive population. Catecholamines, plasma renin activity, and urinary creatinine, sodium, and potassium were measured in recumbent subjects who had received a controlled-sodium diet. Our findings suggest that (1) benign essential hypertension represents a heterogeneous entity and a continuous spectrum of clinical and biochemical changes when it is related to the level of blood pressure, (2) adrenergic involvement is more evident in labile hypertension, (3) regardless of the urinary excretion of catecholamines in subjects with benign essential hypertension the urinary ratio of dopamine to norepinephrine always remains lower, and (4) a negative correlation exists between urinary sodium excretion and usual blood pressure indexes.

Sex Differences in the Urinary Catecholamines

Urinary excretion of dopamine, norepinephrine and epinephrine was measured in a group of adult men and women of comparable age during recumbency and then during stimulation by upright posture. Urinary norepinephrine was found to be significantly higher in women (30.3 +/- 4.4 ng/min/m2 B.S.) than in men (18.3 +/- 2.7 ng/min/m2 B.S.) during recumbency; there was no significant sex difference in dopamine and epinephrine excretion. There was no apparent trend indicating a difference in urinary catecholamine excretion during the follicular or luteal phase of the menstrual cycle. In response to upright posture, there was a significant decrease in the urinary dopamine-norepinephrine ratio in both sexes; the magnitude of the decrease was, however, significantly higher in men (-9.9 +/- 3.0) than in women (-2.05 +/- 0.72). The mechanisms of the sex differences in urinary catecholamine excretion are unknown. Clinical studies involving catecholamines have to take these sex differences into account.

Autonomic Nervous System and Benign Essential Hypertension in Man II. Circulatory and Hormonal Responses to Upright Posture

The effect of upright posture as a physiological stimulus of the adrenergic nervous system was studied in 56 subjects with benign essential hypertension. The subjects received a controlled-sodium diet. Blood pressure, heart rate, catecholamines, plasma renin activity, and urinary creatinine, sodium, and potassium excretion were measured in the recumbent and upright positions. We found an alteration in the blood pressure response in subjects with benign essential hypertension; the postural increase in the mean blood pressure in normotensive subjects (3.18 ± 1.35 mm Hg) progressively disappeared and was replaced by a postural decrease in subjects with more severe stable hypertension (−6.71 ± 2.42 mm Hg). The hypertensive subjects also lacked the usual increase in urinary excretion of norepinephrine. A significant increase in plasma renin activity associated with a significant decrease in plasma norepinephrine occurred in subjects with labile hypertension with postural tachycardia. Finally, we found a highly significant correlation between the excretion of sodium and potassium in the recumbent position and the retention of both ions in the upright position.