Supplementary studies on the sites of action of pilocarpine.

Although it is generally accepted that pilocarpine affects the postganglionic cholinergic receptors and reveals a strong muscarinic action selectively, evidence has been cited to conclude that the drug affects other sites of the effector organs. Large doses of the drug do not induce a rise of blood pressure in an atropinized animal. But Dale and Laidlaw (1), Marrazi (2) and Ambache (3) concluded that pilocarpine stimulated the superior cervical ganglion in the cat, based on the experimental results that the drug potentiated the contraction of the nicti tating membrane and the postganglionic electrical potential in response to preganglionic sympa thetic stimulation. Feldberg et al. (4) proved that pilocarpine induced a discharge of adre naline from the adrenals. The authors all agreed that the ganglion stimulating action of pilocarpine was abolished after the administration of atropine in large doses. The evidence that pilocarpine induced a strong pressor action on the blood pressure after the administration of such ganglion blocking agents as nicotine (5), d-tubocurarine and tetra ethylammonium (6), hexamethonium, laurifoline and menisperine (7) raises the question re