The action of antisympathomimetic drugs on the urinary excretion of adrenaline and noradrenaline.

In cats anaesthetized with pentobarbitone sodium, phenoxybenzamine, dibenamine, phentolamine, and piperoxane reduced the blood pressure and increased the urinary excretion of noradrenaline. When the fall of blood pressure after phenoxybenzamine was prevented by repeated injections of vasopressin, the urinary excretion of noradrenaline did not rise. Hydergine and hydrallazine reduced the blood pressure without raising the urinary excretion of noradrenaline. In dogs, the infusion of small amounts of noradrenaline led to a significantly higher urinary recovery of the amine after phenoxybenzamine than before. It is concluded that antisympathomimetic drugs interfere with the destruction in the body of noradrenaline, whether released reflexly in hypotension or injected.