Effect of cocaine and related drugs on the uptake of noradrenaline by heart and spleen.

Noradrenaline uptake by heart and spleen after intravenous infusion of noradrenaline was measured in the pithed rat. Cocaine, given before the infusion, inhibited the noradrenaline uptake in relation (a) to the dose administered and (b) to the amount of noradrenaline infused. There was an association between increase in the pressor response to a test dose of noradrenaline and inhibition of the uptake by the heart. Drugs related chemically to cocaine, such as alpha-cocaine, amethocaine, and atropine, did not alter the noradrenaline uptake or potentiate the blood pressure response to noradrenaline. The noradrenaline uptake by the heart was unchanged after dibenamine, but blocked by the dichloro-analogue of isoprenaline. It was concluded that cocaine specifically prevented the uptake of noradrenaline by tissues, thus increasing the amount of noradrenaline available for combination with adrenergic receptors. The dichloro-analogue of isoprenaline appeared to block both uptake by the heart and the combination with receptors.