Intravenous yohimbine. Selective enhancer of norepinephrine and cortisol secretion and systolic blood pressure in humans.

Yohimbine hydrochloride was administered intravenously to nine normal volunteers to assess alpha 2-adrenergic receptor function. Plasma catecholamines, cortisol, and psychophysiological parameters (blood pressure, pulse, somatic symptoms checklist, and visual analogue scales assessing mood) were used as dependent variables. Plasma norepinephrine and plasma cortisol increased significantly after yohimbine administration, while epinephrine remained unchanged. Systolic blood pressure and somatic symptoms were also significantly increased by yohimbine. These findings suggest that low-dose intravenous yohimbine is an effective probe for alpha 2-adrenergic receptors and the hypothalamic-pituitary-adrenal axis.