Spontaneous activities of the slow muscle system have been recorded from the forelimb muscles, the 3rd spinal ventral horn, and the midbrain of toad.
1. On the forelimb muscles, slow muscle responses were observed by unipolar leading; in general from extensors and flexors in frequencies 7-12/sec. and 3-6/sec. respectively at rest. From symmetric muscles on the right and the left sides these were often observed discharging almost synchronously. However, their frequencies were varied according to changes in posture.
2. Spontaneous spike discharges were led extracellularly from the 3rd spinal ventral horn with tungsten needles with a tip of about 1μ. These potentials were usually triphasic, and the 2nd negative spike as large as 250 μV was observed commonly. These rhythmic discharges appeared at 7.7/sec. in the mean, and there was found the correspondence to the slow muscle responses, and that synchronization was detected among almost extensors of the forelimbs.
3. Similar spike discharges were also recorded from loci presumably belonging to the brain-stem reticular formation, which distributed uniformly in the mesencephalon and beneath rhomboid fossa. The potential was almost triphasic, the marked negative phase ranging up to about 250-300 μV, and the frequency was almost 7.9/sec. under the stationary condition. The frequency was almost equal to the rhythm of the muscle response in the forelimb, and there could be even found a correspondence between those two trains in simultaneous leading.
4. Histograms have been plotted from intervals between successive discharges led from the brain-stem. The rhythmic discharges are characterized by a peak in the distribution of intervals, usually between 100 and 160, msec. The peak interval was transferred temporarily in the range from 70 to 50 msec. when the labyrinth was stimulated by means of rolling the body about 45°. Repetitive sloping stimuli were most effective, advancing the peak of the interval histogram to 30 msec. and consequently rhythmic activities of the slow system were accelerated in general to about 30/sec. in frequency in its muscles and their centers.

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The direct cortical response (DCR) recorded from the motor cortex has been studied in rabbits. The results should be interpreted as suggesting that the called dendritic potential can be analysed into its component potentials: spike component with a steep rising phase and high amplitude; and slow component (SP) with a slower rise, more variable time course and low amplitude.
1. In experiments of various stimulus strengths the SP occurs generally at weak stimulus, while the high amplitude response appears at strong one. As soon as the response exceeds about 0.5 mV which is usually the maximal value of SP, spike begins to appear, which finally reaches its maximal value with increase in the stimulus intensity.
2. The spike component produced by maximal stimulation holds an absolute refractory period of about 3 msec. This indicates the spike component is an action potential of the responding neurones, presumably of the apical dendrites. On the other hand, SP which can summate without refractoriness shows a behavior of the graded response or postsynaptic potential. No satisfactory evidence has been found to identify the structure responsible for SP.
3. Deterioration of the cortex prevents the spike from its ample development even by a maximal stimulation. In such a case an incomplete summation can be observed which, however, is considered to be a complete summation of the SP component in the response.
4. From the distance-amplitude relation, the larger is the reduction rate (A₁-A₂/A₁·100) the more the spike component is contained in the response, while theresponse showing smaller reduction rate has larger SP component regardless of the absolute amplitude.
5. Superposition of SP on the spike component and vice versa can be recorded, suggesting that there is no mutual dependence between both components.
This work was begun at the Physiological Laboratory, Research Institute of the Applied Electricity, Hokkaido University. The authors take this opportunity of thanking Prof. H. YOSHIMURA for his laboratory facilities to promote this work and acknowledge the cooperation of Drs. T. IKEDA, T. MIZOBUCHI, M. URUHA and H. KITASATO.

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A potential oscillation appears superimposed on the slow potential in the olfactory epithelium of the toad, when an odorous vapour is applied. The properties and generative mechanism of the oscillation were studied.
1. The magnitudes and in many cases the frequencies of the oscillations increased with increasing stimulus intensity or increasing stimulus velocity (III, IV). The frequency decreased linearly or exponentially towards the end during a stimulation (I).
2. The shapes, frequencies, durations and magnitudes of the oscillations are different not only in each toad but also at various sites on the olfactory epithelium of the same toad (II).
3. The durations of the oscillations were elongated with an exponential relation to the durations of olfactory stimulation (V).
4. During repetitive olfactory stimulation, the magnitude, duration and frequency gradually decreased, and even the shape was changed. Eventually, the oscillation disappeared (VI). The oscillation easily shows a fatigue-phenomenon.
5. The potential oscillations appeared differently depending on the kinds of odours (VII, VIII).
6. The potential oscillation was neither produced nor affected by a single or repetitive electrical stimulation of the olfactory epithelium or nerve (X).
7. By covering a part of the epithelium with a vinyl membrane, it was shown that the medial and anterior part of the eminentia was most important for the generation of the oscillation and that the oscillation was not produced by the activity of only a small olfactory area (XI).
8. It was always found that the potential oscillation appears when the slow potential reaches a certain magnitude (III, IV, VII, XI).
9. Small potential discharges were found in the epithelium by micro-electrode. They increased in number and seemingly became synchronized into a potential oscillation with increasing stimulus intensity (XII).
10. It was concluded that the potential oscillations of various magnitudes and shapes are produced by the interaction and summation of the potential discharges recorded by micro-electrode in the olfactory epithelium. A generative mechanism of the potential oscillation was considered.
11. It was also concluded that the potential oscillation does not play any active role in olfactory sensation (VII).

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The effect of light intensity upon the oxygen consumption of the isolated outersegments of rods was studied by means of the Warburg apparatus at 25°C. The outersegments were separated from dark adapted winter toad's retina at 0°C. In the addition of 10-²M 1-glutamate in a suspending medium, the inhibition caused by white light illumination was proportional to the logarithm of light intensity, but, in the absence of glutamate, the inhibition was not proportional to the logarithm of light intensity.

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The changes of the activity of the cardioregulatory and abdominal sympathetic nerves during reflex deglutition were investigated by means of action potential study.
1. The efferent impulses in the cardiac sympathetic nerve were slightly enhanced by pouring the water into the pharyngeal cavity. Then activity was completely inhibited with the occurrence of deglutition. Similar results were obtained by stimulating the central end of the severed superior laryngeal nerve. Such responses could still be evoked after the intravenous administration of succinylcholine.
2. The efferent impulses in the cardiac vagal nerve were slightly increased by the water-pouring. Then activity was transitorily suppressed with deglutition.
3. The tonic activity in the splanchnic nerve, hypogastric nerve and renal branch of the abdominal sympathetic nerves was slightly increased by the water-pouring. Then it was followed by a transitorily complete inhibition which occurred synchronously with each deglutition. Such responses were eliminated by cutting the bilateral glossopharyngeal and superior laryngeal nerves. On the other hand, the activity of the ocular sympathetic nerve was not affected by swallowing.
4. From the experimental results, a diagram showing the activity of the cardioregulatory and vasomotor centers during reflex swallowing was represented.

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Using the glass capillary ultramicroelectrode, the effects of methoxamine upon the membrane resting and action potentials of the ventricular muscle fibres of the guinea pig were examined.
Methoxamine, in doses of 100-200μg/ml, reduced the maximum rate of rise of the rising phase of the action potential considerably without producing any appreciable change in the magnitude of the membrane resting and action potential. The duration of the action potential was moderately prolonged. Concurrently with the changes in the membrane potential, there was observed diminished contraction.
In order to get some informations about the permeability of the resting membrane, the chronaxie for the square wave pulses stimulation was determined. remarkable change in the chronaxie was observed.
The discussion was presented concerning the underlying mechanisms of the change in the pattern of the membrane potential. The possibility of correlating changes with the diminished contraction was discussed.

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1. The ERG potential was recorded from within the frog's isolated retina through the differentially connected inner and outer pipettes of a pencil-type microelectrode, the inner pipette being protruded a fixed distance of 50μ out of the tip of the outer pipette. The insertion of the electrode was made from the receptor side. At the depth where a maximal ERG potential was obtained between the two pipettes, ferricyanide ions in the inner pipette were expelled electrophoretically to combine with ferrous ions applied from outside the retina and to form a small spot of Turnbull's blue in the tissue around the tip of the inner pipette.
2. The blue spot was regularly detected in the distal half of the inner plexiform layer, indicating that the main ERG layer lies between this depth and the depth 50μ nearer to the receptors. This corresponded roughly to the bipolar cell layer. The whole ERG layer showed a wider distribution to both sides of this main layer.
3. At the retinal region where the rod outer segments were removed, only the PIII component was obtained, isolated from the PII. Depth recording from such a region by means of the differentially connected pipettes and later histological location of the site of recording reaffirmed our earlier conclusion that the PIII originates from about the same depth as the PII.

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1. In the orthodromic perfusion of the denervated colonic loop of dogs with the normal saline solution, the preexisting waves, antidromic waves, are reinforced with a rise of pressure within the range from 0 to 12 cm H₂O, however, without any outflow of fluid. When the pressure is raised higher than the level mentioned just, the orthodromic waves originate in the oral end of the loop, becoming more and more powerful with increase of the pressure and thus resulting in a remarkable outflow of fluid.
2. Provided HCl solution is used as the perfusing fluid, the events described above not only proceed more rapidly in succession but also occur more vigorously than those observed in the loop perfused with the saline solution. On the contrary, this succession of events does not occur where the mucosa previously has been cocainized.
3. In the antidromic perfusion the outflow of fluid does not occur, because the enormous rise of tone, which is especially remarkable in the oral half of the loop, makes an extreme narrowing of the lumen of the loop. However, this phenomenon does not appear, provided the mucosa has been cocainized previously.
4. From the results described above it may be concluded that the mucosal intrinsic reflex regulates the strength and the direction of contraction waves of the colon: The reflex reinforces the preexisting antidromic waves under a lower intraluminal pressure, favouring the contents to accumulate, whereas it elicits the orthodromic waves under a higher pressure, favouring the contents to be propelled anally.

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1. By means of a coaxial pencil-type microelectrode, simultaneous intra-and extracellular recording was made of the action potential of the toad's sartorius muscle fiber and the crayfish giant axon. Stimulation was made at a point some 3 mm distance from the site of recording.
2. Depending on the preparation used and also on the time for which the membrane has been impaled, the configuration of the extrap was various, even when the intrap was about normal; from configurations more like the intrap itself to those similar to its second derivative, with configurations resembling the first derivative of the intrap in between.
3. In recordings immediately after the membrane was impaled, the extrap of the muscle fiber resembled most frequently the first derivative of the intrap, while that of the giant axon was usually triphasic and similar to the second derivative of the intrap.
4. The state of the local membrane corresponding to each configuration of the extrap was discussed. The “efflux mechanism” in the membrane appeared to be more susceptible to impalement than the “influx mechanism”.

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1. The effect of GABA on blood pressure of normotensive and hypertensive rats or men was investigated.
2. GABA, when administered orally one g per day for a month, did not cause any appreciable changes in body weight, blood pressure and other side effects in normotensive rats. No histological changes were found in their organs.
3. On the contrary, GABA reduced the elevated blood pressure of experimental renal hypertensive rats at the doses of more than thirty mg per day. Its effect was maintained during the application, and disappeared within one week after the interruption of treatment.
4. When glutamate or aspartic acid of 50 mg per day was orally applied for three weeks, no change was observed in blood pressure of hypertensive rats.
5. GABA, administered subcutaneously was also more effective in hypertensive rats than in normotensive ones.
6. Subcutaneous injections of GABA (1-3 mg per kg) on normotensive subjects produced slight uncomfortable side effects.
7. GABA, if administered orally three g per day, did not cause any appreciable effects on normotensive persons, but it lowered remarkably the elevated blood pressure of patients.

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1. Excitatory postsynaptic potentials (e. p.s. p.'s) of the giant nerve cell system of Onchidium verruculatum were investigated by intracellular electrode technique.
2. An impulse of a single presynaptic fibre was usually too small to initiate a postsynaptic spike and spacial and temporal summation was necessary to produce the postsynaptic spike.
3. The increase of calcium or magnesium concentration in the external medium increased or decreased the amplitude of the e. p.s. p.respectively but the maximum amplitude of the synaptic potential reached by repetitive presynaptic stimulation was practically unchanged.
4. From the above results the temporal facilitation is produced by increasing the active area of the synaptic membrane innervated by a single presynaptic fibre.

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1. Medullectomized rats showed a diminished diuretic response to ingested water.
2. Subcutaneous injection of adrenaline in a small dose, which failed to increase urine output in normal rats, caused an increase in the water excretion rate of medullectomized rats. Treatments with adrenaline, 2 hours prior to water load or successively for 3 to 4 weeks, restored the lowered diuretic response of medul lectomized rats to normal level.
3. Pitressin was more effective to elicit antidiuresis in medullectomized rats than in normal ones.
4. Vasopressin inactivating capacity of liver tissue was reduced after medullec tomy. The reduced inactivation restored to normal level after treatments with adrenaline. In vitro addition of adrenaline into incubation medium of liver homogenate did not affect the inactivating system.
5. Serum from medullectomized rats contained more antidiuretic activity than that from normal rats. The accumulation of antidiuretic material in serum in the absence of adrenal medulla could be prevented by chronic treatments with adrenaline.

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