Increased urinary excretion of adrenaline and noradrenaline after phenoxybenzamine.

In dogs anaesthetized with pentobarbitone sodium phenoxybenzamine greatly increased the urinary excretion of adrenaline and noradrenaline. This was associated with a transient increase in the volume of urine excreted and a fall in blood pressure. Hexamethonium prevented the effects on the urinary amines and on the blood pressure. Methacholine hypotension induced an increased adrenaline excretion, but no change in noradrenaline. The excretion of adrenaline released following ganglionic stimulation by acetylcholine did not appear to be affected by phenoxybenzamine, but that of noradrenaline was increased. During infusions of adrenaline or noradrenaline, phenoxybenzamine increased the excretion of both adrenaline and noradrenaline.