1. Eleven patients with essential hypertension and nine healthy normotensive volunteer subjects, all without a neurological disorder, had blood drawn and cerebrospinal fluid sampled for analysis of noradrenaline (NA).
2. Cerebrospinal fluid NA levels were elevated (P<0.01) in the hypertensive patients but plasma levels of NA were similar between groups.
3. The results suggest there is noradrenergic hyperactivity in the central nervous system which is not reflected in abnormal peripheral sympathetic nervous system function in this group of patients.