Search PubMed⌕ Search

Biomedical subjects

I Uramoto

Publications and source records attributed to I Uramoto.

35 records · Page 2Linked to original sources
PubMed1984

Ontogenetic aspects of changes in muscular potentials at medial gastrocnemius muscles of dystrophic mice due to prolonged stimulation.

Changes in muscular potentials at medial gastrocnemius (MG) muscles induced by prolonged stimulation at 5 Hz were compared in dystrophic mice and their normal littermates at various ages. A rapid and notable reduction in the amplitude of muscular potentials at MG muscles was observed in normal mice. This was in contrast with a slight decrease or even an increase in the amplitude in dystrophic mice. The magnitude of reduction in normal mice increased with age, but in dystrophic mice where the change (a decrease or even an increase) was slight, it was similar in extent regardless of age. The slight change in dystrophic mice under the present regimen would be called a fatigue, resistant-like property, and this was discussed in conjunction with analogous properties observed in electrophysiological, histological and biochemical fields.

Animals↗
PubMed1983

Contrast of time courses of changes in muscular potentials to prolonged stimulation at 5 Hz in rat medial gastrocnemius and soleus muscles.

Time courses of changes in muscular potentials to repetitive stimulation at 5 Hz for 10 min were compared between rat medial gastrocnemius (MG) and soleus (SOL) muscles. Stimuli were applied to a sciatic nerve near the entrance of the MG and lateral gastrocnemius (LG) muscles and its exit segment from the LG to the SOL muscles. Muscular potentials were generally evoked in the form of a biphasic wave at the MG muscle and were always of a simple biphasic pattern at the SOL muscle. It was found that, due to prolonged stimulation, muscular potentials were rapidly and notably reduced in the MG muscle, whereas they were gradually facilitated in the SOL muscle. This contrast was similar to differences in the time course of changes in muscular potentials under these conditions in the MG muscle of dystrophic and littermate normal mice.

Animals↗
PubMed1982

Different time courses of reduction in muscular potentials to moderate frequency stimulation in dystrophic and normal mice.

Muscular potentials were evoked by electrical stimulation of sciatic nerves and recorded from gastrocnemius muscles in dystrophic and normal mice. When frequency of stimulation was accelerated from 0.5 to 5 per sec and continued, the potentials were depressed to a notable extent in normal mice, whereas only a slight decrease or even an increase in them was observed in dystrophic mice. Thus, a simple method has been developed to differentiate pre- and/or postjunctional properties for impulse transmission in dystrophic mice from those in normal mice.

Action Potentials↗
PubMed1975

A late component of flash-evoked potentials in the cat's optic chiasma and superior colliculus: its appearance due to background illumination.

Flash-evoked potentials (FEPs) in the cat's optic chiasma and superior colliculus were recorded under the following two conditions: complete darkness and background illumination. Special attention was paid to a specific late component of FEP'S and comparison in the behavior of the late component was made between the two conditions. It was found that a late component of FEPs in the optic chiasma appeared in the presence of background illumination while it was not observed under the condition of complete darkness. A corresponding late component of FEPs was detected in the superior colliculus. The late component might be supposed to be driven from a class of W-cells in the cat's retina.

Animals↗
PubMedDate not supplied

Recycling process of acetylcholine in the rat muscle controlled in a short-term memory manner.

The recycling process of acetylcholine (ACh) was studied in reference to muscle potentials evoked by sciatic stimuli in the presence of neostigmine. Wistar rats around 20 days old were anesthetized with urethane. Muscle potentials were recorded with concentric electrodes from their exposed medial gastrocnemius muscles before and after the injection of neostigmine. Attention was paid to changes in muscle potentials evoked by a set of 3 stimuli, and comparison was made mainly between successive two sets. Three potentials before neostigmine treatment were similar in amplitude. When a set of 3 stimuli was delivered 8 min after it, the first potential was as large as that before it. The others were greatly depressed. The first potential evoked by a set of 3 stimuli 10 min after neostigmine treatment showed a similar amplitude to the control level. The other potentials were again reduced severely. However, none of them were depressed so much when 3 stimuli were delivered 11 min after the drug application. When two sets of 3 stimuli were given with an interval of one minute, it was repeatedly observed in all animals that muscle potentials evoked by the second set were influenced by the first set. The second potential evoked by the second set was not so much depressed as seen when the interval was two or more minutes. Thus, a striking contrast was observed between successive two sets of 3 stimuli with an interval of one minute. These results indicate that the recycling process of ACh was activated following impulse transmission in rat muscles, and suggest that there exists such a neural mechanism as can exert an influence on the process in a short-term memory manner.

Acetylcholine↗
PubMedDate not supplied

Neostigmine-induced characteristics of spontaneous activities and evoked muscle potentials in rat gastrocnemius and soleus muscles.

Using concentric electrodes, spontaneous activities and evoked muscle potentials were recorded from medial gastrocnemius (MG) and soleus (SOL) muscles of Wistar rats about 60 days old. When neostigmine methylsulfate was injected, spontaneous activity such as motor unit discharges occurred in a burst in the MG muscles, in contrast to few activity before the injection of this drug. In the SOL muscles, only single spikes were sometimes observed after it. In coincidence with burst discharges, some oscillations were definitely observed following the main component of MG potentials evoked by single stimuli to a sciatic nerve, whereas only slight deflections could be detected in SOL potentials. Thus, different modification of spontaneous activities and evoked muscle potentials were induced in MG and SOL muscles by the injection of neostigmine methylsulfate.

Animals↗
PubMedDate not supplied

Different changing patterns of soleus potentials due to repetitive stimulation in young and old rats.

Time courses of changes in medial gastrocnemius (MG) and soleus (SOL) muscle potentials induced by repetitive stimulation at 5 Hz were studied using Wistar strain rats. Particular interest was focussed on the changing pattern of SOL potentials in old rats as compared with that in young ones. Contrary changing patterns of SOL potentials were found in young and old rats. SOL potentials were rapidly reduced to respective plateau levels in old rats while they were gradually potentiated in young ones when 5 Hz stimulation was given for 10 min. Moreover, the pattern obtained from middle aged rats fell between those of the two age-groups.

Aging↗