[Effects of cocaine on calcium exchange studied in rat duodenum].

On rat duodenum, previously decalcified, cocaine enhances notably the increase of the tonus brought about by an addition of Ca ions. Similarly, cocaine enhances the fall of tonus which follows the decalcification of an organ immersed initially in normal Tyrode. This effect of cocaine on Ca2+ exchanges may be put forward as an explanation of the well known sensitizing effect of this alcaloid towards several agonists especially noradrenaline and other sympathomimetic amines.