Role of Endogenous Nitric Oxide in Circadian Blood Pressure Regulation in Healthy Humans and in Patients with Hypertension or Atherosclerosis

Abstract

There is significant circadian variation in urinary nitrate and cyclic GMP excretion rates, two marker molecules for systemic NO production, in healthy humans. NO production is increased in the morning, concomitantly with the morning increase in blood pressure, indicating that NO may buffer blood pressure increase. Diurnal variation in nitrate and cyclic GMP excretion is absent in HT, pointing to impaired NO formation. The major change in PAOD is increased nitrate/cyclic GMP ratio, which points to increased oxidative inactivation of NO in this disease. Disturbed formation and activity of NO may contribute to blood pressure alterations in cardiovascular disease.