Circulating levels of corticotrophin and cortisol after infusions of L-DOPA, dopamine and noradrenaline, in man.

Intravenous infusions of noradrenaline and dopamine in normal saline, and L-dopa in sodium lactate, were given to seven patients with Parkinsonism, and to five healthy volunteers. Infusions of saline and lactate were given, in a similar manner, to six additional healthy volunteers, who formed a control group. Dopamine and noradrenaline were each given in gradually increasing doses, for periods of 4 min, until a 30% increase in systolic blood pressure had occurred. L-Dopa (320 mg) was given a constant rate of infusion over 80 min. Plasma fluorogenic corticosteroids (cortisol) increased with dopamine , and decreased with noradrenaline. These changes were significantly different from the control group in the case of noradrenaline only. ACTH values changed in a similar manner. L-Dopa produced a consistent rise in both ACTH and cortisol that was significantly different from control subjects. The implications of these observations are discussed.