1. Mechanical stimulation on dorsal surface of the spinal cord can evoke the scratching movement in decerebrate cats.
2. The area to evoke the scratch movements is located on the dorsal surface of the cord 2mm lateral to the dorsal central spinal artery at the level of C₁ and C₂. The movements lasted for 4-34 sec. and the latency ranged from less than 1 sec. to 4 sec. and the frequency was 1-4 per sec.
3. In cats anesthetized with pentobarbital, the scratching movements could not be elicited.
4. Pinna, galloping and stepping reflex movements were also evoked by mechanical stimulation of various levels of the spinal cord in decerebrate cats.

View full abstract

The finger temperature responses to local cooling were examined on 8 groups of Japanese subjects and one group of Ainu in Hokkaido. The responses were low in Japanese subjects born on the main island in comparison with the values of subjects born on Hokkaido. The responses of Ainu were not greatly different from those of Japanese farmers in Huren, fish factory workers in Monbetsu and male students in Sapporo, but significantly higher than the responses of policemen, nurses and girl students in Asahikawa and fishermen in Monbets
Summarized results indicated that the responses of subjects in Hokkaido, particularly of Ainu, were considerably higher than the average values reported previously on Japanese subjects.

View full abstract

1. Effect of grayanotoxin 1 on the soleus and extensor digitorum longus muscles of rats was studied by the electrophysiological methods.
2. Grayanotoxin 1 has an inhibitory effect on the initiation of action potentials of fibers of both muscles. This toxin causes a gradual decrease of the resting potential and an elevation of the critical firing level.
3. As decrease in resting potential induced by this toxin was always associated with reduction of the effective membrane resistance and these phenomena were not observed upon withdrawal of Na from the medium, depolarization of the membrane in the toxic solution is considered to be due to increased permeability of the membrane to Na ions.

View full abstract

1. Isolated muscle spindles in the frog sartorius muscle were perfused in Ringer solutions made hypotonic by reducing NaCl or hypertonic by addition of NaCl, Na₂SO₄, Na₂HPO₄+NaH₂PO₄, sucrose, urea, glycerol, or propylene glycol.
2. The frequency of spontaneous discharge at the in situ length of the muscle increased both in hypo- and hypertonic solutions.
3. Both the dynamic and static components of the spindle potential during the stretch of the muscle increased in amplitude upon exposure to hypotonic solutions, while they decreased in hypertonic solutions.
4. Dynamic and static responses of the spindle discharges during the muscle stretch increased in hypotonic solutions, while they decreased in hypertonic solutions.
5. Changes in responses of the spindle receptor in the hypo- or hypertonic solutions were neither caused by changes in the steady potential along the sensory terminals nor by those in tension of the muscle fibers.
6. The responses of spindle receptors in solutions with various osmolalities were discussed in terms of changes of ionic concentration in an interspace between the terminal axon and the surrounding Schwann process.

View full abstract

Experiments have been done on the A-V conducting fibers of the toad heart and rabbit heart to examine the nature of the A-V conduction.
The configuration of the conducted transmembrane action potentials was found to depend on the direction of impulse propagation. However, there was no obvious relation between the rate of rise of the action potential and the distance the impulse had travelled in the A-V conducting pathway.
The unique change of shape of the action potential recorded from the atrial margin of the A-V conducting pathway of the toad heart after stimulation of the vagus nerve was not seen when the heart was driven antidromically. Sometimes a summation of action potentials was observed after stimulation of the cardiac nerve.
From these results, it is concluded that heterogeneous structure of the A-V conduction systems, as shown by the differential interference microscopy, is responsible for the A-V conduction delay.

View full abstract

1. Aconitine-induced arrhythmias of the isolated rabbit atria and ventricles, recorded by the microelectrodes, disappeared in the Na-free choline-substituted Tyrode solution.
2. Tetrodotoxin antagonized the aconitine-induced irregular electrical activity of the atria and ventricles, restituting the regular rhythms.
3. MnCl₂ which affects the Ca permeability did not abolish the aconitineinduced irregular activity of the atria and ventricles
4. These data indicate that the principal cause of aconitine-induced irregular firing of the atria and ventricles seems to be due to enhancement of the rapid inward Na current.

View full abstract

1. Enhancement of the gustatory responses in single chorda tympani fibers of rats, produced by the addition of 5'-ribonucleotides to MSG, was investigated.
2. No fibers were found which were exclusively responsive to MSG or one of 5'-ribonucleotides. Fibers responsive to MSG also gave responses to 5'-ribonucleotides. Marked enhancement of the magnitude of response by replacing one-tenth of MSG with 5'-GMP, 5'-IMP or 5'-AMP was observed in fibers responding well to sucrose but not in those predominantly sensitive to NaCl, the magnitude of potentiation produced being 5'-AMP=5'-GMP>5'-IMP. The enhancement by 5'-UMP and 5'-CMP was small.
3. A highly significant correlation was observed between the magnitude of response to the mixture of MSG with 5'-GMP, 5'-IMP or 5'-AMP and that for sucrose and saccharin, thus showing the similarity of the quality of taste between the two. On the other hand, the magnitude of response to the mixture of MSG with 5'-UMP is significantly correlated with that for NaCI but not with the response magnitude for sucrose.
4. Fibers predominantly sensitive to sucrose elicited rhythmic bursts of impulses in response to, not only, sucrose and saccharin, but also to the mixture of MSG with 5'-GMP, 5'-IMP or 5'-AMP, the period of the bursts being several hundred msec.
5. A highly significant correlation was observed between pairs of responses to MSG4-51-GMP, MSG+5'-IMP and MSG+5'-AMP, indicating similarity of quality of taste among each other. However, correlations between the former three and MSG+5'-UMP are small, suggesting a difference in taste quality.
6. Equations were calculated for expressing the neural response magnitude for MSG, 5'-ribonucleotides and their mixtures by those for the four basic gustatory stimuli.
7. Based on the results of the experiments it has been postulated that glutamate ions combine with sucrose-sensitive receptor-molecules and that 5'-GMP, 5'-IMP and 5'-AMP facilitate binding of the latter with the former.

View full abstract

The movements of the villi were studied in anesthetized dogs. The results are summarized as follows:
1. The villi shorten quickly at irregular intervals and then extend slowly, each villus contracting about 10-28times per minute quite independently of its neighbours.
2. The activity of the villi is greater in the upper part than in the lower part of the small intestine.
3. Stimulation of the cervical vagus nerve caused a slight increase in the activity of the villus, while stimulation of the splanchnic nerve and mesenteric nerve inhibited its activity.

View full abstract