Muscle relaxant action of MS-322, a new centrally acting muscle relaxant, in rats.
1. The pharmacological properties of (R)-(+)-3-phenyl-5-¿2-(1-pyrrolidinylmethyl)-butyryl¿isoxazole hydrochloride (MS-322) were investigated and compared with those of other muscle relaxants. 2. MS-322 (3-12 mg/kg, IV) reduced spinal reflex potentials in acutely spinalized rats dose dependently. Its inhibitory effects on polysynaptic and dorsal root reflexes were more marked than those on the monosynaptic reflex. 3. MS-322 (1.5-12.0 mg/kg, IV) depressed the afferent discharges of de-efferented muscle spindles in anesthetized rats dose dependently. 4. The inhibitory effect of MS-322 on this afferent activity was considered to be due to its membrane stabilizing action. 5. In addition to the central effects of MS-322, its effect on muscle spindles may contribute to its muscle relaxant activity.
Otsu
T
T
Department of Toxicology and Pharmacology, Faculty of Pharmaceutical Sciences, University of Tokyo, Japan.
Nagao
T
T
Ono
H
H
D000818:Animals; D003655:Decerebrate State; D007555:Isoxazoles / Q000494:pharmacology*; D008297:Male; D009046:Motor Neurons / Q000187:drug effects / Q000502:physiology; D009125:Muscle Relaxants, Central / Q000494:pharmacology*; D009126:Muscle Relaxation; D018482:Muscle, Skeletal / Q000187:drug effects / Q000502:physiology; D009475:Neurons, Afferent / Q000187:drug effects / Q000502:physiology; D011759:Pyrrolidines / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D012018:Reflex / Q000187:drug effects*
D007555:Isoxazoles; D009125:Muscle Relaxants, Central; D011759:Pyrrolidines; C107564:3-phenyl-5-(2-(1-pyrrolidinylmethyl)butyryl)isoxazole hydrochloride