Effects of aconitine on neuromuscular transmission and the superior cervical ganglion

Contractions of diaphragm, tibialis muscle and nictitating membrane were caused by stimulation of nerve (phrenic and peroneal nerve) or preganglionic sympathetic nerve in the preparation of rat phrenic nerve-diaphragm, cat tibialis and cat superior cervical ganglion. Aconitine (Ac) initially enhanced the contractions of the muscles described above then inhibited them. During enchaned con contraction of diaphragma and tibialis muscle, the tension of them is also increased concomitantly. When the bibialis muscle and nictitating membrane were inhibited by Ac, the amplitudes of a single twitch caused in them by ia (anterior tibial and lingual arterial injection) acetylcholine (ACh) were almost the same as those of a single twitch caused by ia Ach of the same dose before treatment with Ac. Inhibitory effect of Ac on contraction of diaphragm was antagonized by Ca2+, but enhanced by d-tubocurate and physostigmine.