[Effects of 4'ethyl-2-methyl-3-piperidinopropiophenone on experimental rigidity and spinal cord activities (author's transl)].

Effects of 4'ethyl-2-methyl-3-piperidonopropiophenone hydrochloride (EMPP) on experimental rigidities in rats and spinal cord activities in cats were studied. EMPP in a dose range of 1.25 approximately 10 mg/kg i.v. reduced EMG spikes of the intercollicular decerebrate rigidity and anemic decerebrate rigidity in rats. In alpha-chloralose anesthetized cats, EMPP in a dose range of 2.5 approximately 10 mg/kg i.v. caused a dose-related inhibition of the flexor reflex without any effect on the patellar reflex. In spinal cats, 2.5 approximately 10 mg/kg of EMPP caused a dose-related inhibition of the flexor reflex but the potency was less than that in anesthetized cats. Oral administration of EMPP 100 approximately 200 mg/kg produced a selective inhibition of the flexor reflex and the effect was twice as potent as tolperisone and chlormezanone. On the other hand, EMPP at 2.5 approximately 10 mg/kg i.v. which had little effect on the patellar reflex inhibited both monosynaptic and polysynaptic reflex potentials recorded from the ventral root to the same extent and also depressed dorsal root reflex potential recorded from the dorsal root in spinal cats. EMPP reduced the frequency of spontaneous gamma-motoneurone discharges in spinal cats, but had no appreciable effect on GIa discharges from muscle spindle of the triceps surae muscle. These results indicate that EMPP reduces alpha- and gamma-efferent activities and that EMPP exerts a marked inhibitory effect on spinal cord activities acting on the spinal cord and supraspinal structures.