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Biomedical subjects

Y Kudo

Publications and source records attributed to Y Kudo.

At least 397 records · Page 22Linked to original sources
PubMed1977

Effects of beta-(p-chlorophenyl)-GABA (baclofen) on spinal synaptic activity.

In the isolated perfused spinal cord of the bullfrog, baclofen caused a reduction in the rate of spontaneous discharges in the ventral root at lower concentrations than GABA. The inhibitory effect of baclofen was fully present in a chloride-free medium, whereas that of GABA was markedly reduced. In contrast to GABA, which depolarized the dorsal root, baclofen produced a hyperpolarization in the dorsal root. Moreover, baclofen produced a hyperpolarization in the ventral roots. In the rat, the development of spinal reflex inhibition by baclofen was slow and the effect was long-lasting. Baclofen decreased dorsal root reflexes, suggesting a decreased excitability of presynaptic fibres. Baclofen produced a more pronounced and faster inhibitory effect on monosynaptic reflexes than on polysynaptic reflexes. In the monoamine depleted rat, the effect of baclofen on both types of reflexes was markedly reduced. It appears that catecholamines are involved in the effects produced by baclofen.

Action Potentials↗
PubMed1977

[Pharmacological study on 5-(o-chlorophenyl)-1-methyl-7-nitro-1,3-dihydro-2H-1,4-benzodiazepin-2-one (ID-690), with special reference to the effects on motor systems].

Effects of ID-690 on motor systems were compared with those of clonazepam, diazepam and nitrazepam. ID-690 exerted muscle relaxant action in the rotarod method using rats and mice; this action was almost equal in potency to clonazepam and nitrazepam and more potent than diazepam. Pretreatment with ID-690, clonazepam and nitrazepam increased the sleeping time of mice under thiopental anesthesia to the same degree, whereas diazepam produced a lesser effect. ID-690 was almost equal in potency to diazepam and nitrazepam in protecting against oxotremorine-induced tremor in mice, and approximately 10 times as potent as clonazepam. The anticonvulsant action of ID-690 was similar to that of clonazepam. These benzodiazepines effectively augmented the dorsal root reflexes, while showing no effects on the ventral root reflexes. Rigidity in rats due to anemic decerebration was not affected after intraduodenal administration of these drugs, while phasic augmentation of the rigidity by mechanical stimulation of the hind limb was clearly depressed. These drugs had no effects on the neuromuscular junction. From these results, it is concluded that ID-690 has a wider pharmacological spectrum than clonazepam, is almost equal in potency to nitrazepam and is more potent than diazepam.

Animals↗
PubMed1976

[Effect of drugs affecting sodium permeability on the muscle spindle of frogs].

Afferent discharges of about 10 Hz were recorded in the nerve from the isolated muscle spindle of the m. extensor longus digiti IV of the bullfrog subjected to a sustained stretch. When grayanotoxin-I, ventridine or aconitine was added to the Ringer's solution, the rate of discharges markedly increased and thereafter decreased. In these terms of decrease of discharges, abortive spikes were observed. The rate of discharges was markedly decreased by the application of procaine, diphenylhydantoin, chlorpromazine or tetrodotoxin. With the latter three drugs, abortive spikes were observed in the course of decrease of discharges. Increase of the discharge rate induced by grayanotoxin-I, veratridine and aconitine was antagonized by procain. No alteration was evident in the conduction of afferent discharges, when test drugs were applied to the nerve trunk in concentrations sufficient to change the rate of discharges when applied to the muscle spindle. These results suggest that the rate of the muscle spindle discharges is closely related to sodium permeability of the membrane.

Aconitine↗
PubMed1976

[Effects of divalent cations on the muscle spindle of frogs].

Afferent discharges were recorded in the nerve from the isolated muscle spindle of the m. extensor longus digiti IV of the bullfrog. Discharges of about 10 Hz generated by a sustained stretch were reduced concentration-dependently when Ca2+, Mg2+ or Mn2+ (1.0 approximately 8.0 mM) was added to normal Ringer's solution containing 2.0 mM Ca2+. In terms of the decrease of discharges following the addition of Ca2+ or Mn2+ (4.0 mM), abortive spikes were observed. With an excess of Mg2+ (4.0 mM), abortive spikes were not apparent. Removal of Ca2+ from the Ringer's solution caused an increase in the rate of discharges, and normal levels were restored by the addition of Ca2+ (2.0 mM), Mg2+ (2.3 mM) or Mn2+ (1.8 mM). Application of much higher concentrations of these ions to the nerve trunk produced no alterations in the conduction of afferent discharges. It appears that Ca2+ in the external medium contributes to the inhibition of the mechanism responsible for generating afferent discharges in the muscle spindle and that Ca2+ action is not specific since Mg2+ and Mn2+ can act as substitutes for Ca2+ to regulate afferent discharges.

Afferent Pathways↗