[Synchronized circadian blood pressure rhythm and sympatho-adrenergic activity]

Circadian blood pressure rhythm exhibits a typical biphasic pattern in normotensives and in patients with primary hypertension. It is, however, disturbed in patients with secondary hypertension. There is ample evidence suggesting a major role for the sympatho-adrenergic system in regulating this rhythm. In order to investigate this relationship more accurately, the sympatho-adrenergic activity was studied in 20 patients with normal blood pressure, 20 patients with primary hypertension, and in patients with several diseases characterized by an abnormal catecholamine secretion, e.g. two pheochromocytomas, one adrenomedullary hyperplasia, and two Shy-Drager syndromes. Catecholamine concentrations were measured in plasma and urine, cAMP concentrations in plasma or in lymphocytes, and beta-adrenoceptor density and affinity on lymphocytes, and 24-h blood pressure monitoring was conducted. The data shows synchronicity of the circadian blood pressure rhythm and the sympatho-adrenergic activity both in normotensives and in patients with primary hypertension with normal circadian rhythm, and in abnormal catecholamine secretion with an abnormal circadian blood pressure curve. It is concluded that sympatho-adrenergic mechanisms play an important role in controlling and regulating circadian blood pressure.