Cycrimine on rat diaphragm.

Cycrimine hydrochloride, an anti-Parkinson drug having central cholinolytic properties, was found to cause neuromuscular blockade in the isolated rat diaphragm preparation. The neuromuscular blockade by cycrimine remained unaffected in presence of neostigmine and tetraethylammonium. Lower concentrations of cycrimine potentiated the paralytic effect of d-tubocurarine. A similar paralytic effect of cycrimine was observed in the pharmacologically denervated rat diaphragm. Responses to acetylcholine administered by retrograde i.v. injection were found to be inhibited in presence of cycrimine. These results suggest that the neuromuscular blockade by cycrimine is produced by a postsynaptic direct effect on the muscle.