In search for higher cardiovascular centers, the brain of the toad was explored with a pair of stimulating electrodes, separated about 0.3mm apart, when efferent discharges in the cardiac and splanchnic nerves were being observed. In the dorsal part of the diencephalon tetanic stimulation of 10-50/sec inhibited sympathetic spontaneous discharges in these nerves and excited vagal discharges in the cardiac nerve. On the other hand, in the ventral part of the diencephalon, stimulation caused an increase of sympathetic discharges and a reciprocal decrease in vagal discharges. Thus stimulation of the dorsal diencephalon slowed heart rate and that of the ventral diencephalon accelerated it. It may be concluded that, in the toad as in mammals, there exist in the diencephalon the centers for an integrative control of the cardiovascular systemthrough both sympathetic and parasympathetic nerves.

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The influence of vasopressin on the adrenal catecholamine secretion was investigated in rats. Neither a single intraperitoneal injection of 1 U vasopressin per 100g body weight nor repeated injections of 0.4-0.8 U vasopressin per 100g body weight by 10 times resulted significant change in the catecholamine content in the adrenal gland. 1.5mg of acetylcholine per 100g body weight failed to produce any significant change in the adrenal catecholamine content. Combined administration of acetylcholine with vasopressin showed no effect either.
The adrenaline content of the adrenal venous blood collected for a 10-minute period significantly rose during vasopressin infusion in dose of 100 mU or 500 mU in 5 out of 11 experiments, while no change in noradrenaline was observed. 2U vasopressin, however, seemed to possess a suppressive effect on the catecholamine secretion. 500 mU of vasopressin simultaneously administered with acetylcholine augmented the latter's action to increase the adrenaline output, but not noradrenaline. Since the extent of this augmentative effect far exceeded that accounted for by a simple additive effect, vasopressin was considered to potentiate the action of acetylcholine to stimulate the adrenaline secretion from the adrenal medulla.

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A unitary reflex spike was recorded from the central cut end of ventral root filaments in decerebrated cats.
The lateral and medial gastrocnemius nerves were stimulated by a single shock to each of them. If the interval between the two shocks was within some 30msec and both were kept subthreshold with respect to the reflex discharge, the second of them was found to elicit a reflex spike. The reflex spike was undoubtedly produced by temporal and spatial summation of afferent impulses ascending through the two branches of the tibial nerve. Relation between shock intervals and response times was obtained. The response times were delayed at short intervals, and it was possible to draw four straight lines through each set of points in the graph of this relationship. Analysis suggests that the second postsynaptic potential was summed during the rising phase of the first postsynaptic potential.
In order to restrict the experiment to temporal summation alone, a unitary reflex spike was evoked by double shocks to the same muscular afferents. Although the intensity of each shock was subthreshold for reflex discharge, a reflex spike occurred after the second shock. The relation between the response time and the shock interval was obtained. As in the previous case of both temporal and spatial summation, it was again possible to draw four straight lines in the graph of this relationship. The slope of one line at short intervals serves to explain the relation between the rising rate of the postsynaptic potential and the critical threshold level. From the results it follows that the summed postsynaptic potential, as the inter-shock interval is prolonged, takes progressively longer time to reach the critical level for motoneurone firing during the production of postsynaptic potential. Analysis suggests that this delay is due to rise of threshold owing to accommodation of the motoneurone. The slope constant of relation between inter-shock interval and response time in tonic motoneurones differs from that in phasic motoneurons in a manner which suggests that accommodation is greater in the latter.
Differences between responses in tonic and phasic motoneurones to quick muscle stretch are attributed in part to differences in synaptic transmission.

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1. With the microsomes not preincubated with ATP, the incubation of the microsomes with Salyrgan for a certain period of time was required for obtaining a maximum inhibition of the relaxing activity of microsomes. When the microsomes were preincubated with ATP, the period was more extended than that in the former case. In the latter case, no spontaneous recovery of relaxing activity appeared by further incubation.
2. When raised to a concentration 1.0×10^-5M, Salyrgan inhibited completely the relaxing activity of microsomes, but did not that of relaxing substance. Salyrgan inhibited completely the latter activity at high concentrations above 3.0×10^-5M.
3. The relaxing action of EDTA or pyrophosphate was observed even in the presence of Salyrgan at high concentrations, at which the action of the relaxing substance was inhibited.
On the basis of these results, the mechanism of the inhibitory action of -SH reagents on the relaxing action of the microsomes and that of the action of the relaxing substance were discussed.

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Activity in hypothalamic supraoptic nuclear cells was recorded with microelectrodes in hemispherectomized, chloralose-anesthetized cats. Repetitive stimulations of skin afferents augmented activity of some units but inhibited others. Activity of units was little affected by decortication and removal of the caudate nucleus but considerably increased by decerebellation, midbrain transection and separation from thalamic connections. Stimulation of the stalk augmented rate of firing of nuclear units. Complete isolation of the supraoptic nuclear region from all neural connections except with hypophysis resulted in an increase in cellular discharge rate which lasted for many hours. This augmented activity was associated with a decreased urine output until the pituitary stalk was sectioned. The supraoptic nuclear cells in the island retained their sensitivity to osmotic changes in the blood produced by intracarotid injection of hypertonic glucose.Stimulation of the cerebellar cortex by application of glutamic acid increased urine output. These experiments provide evidence that the supraoptic nucleus cells in addition to being subject to excitation by both neural and humoral agents are under inhibitory control from structures within the cerebellum, midbrain and thalamus.

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1. The effect of single shock stimulation of the cerebral peduncle on the excitability of the Betz cell was studied in locally anesthetized and immobilized cats.
2. The peduncular stimulation produced a prolonged depression of the excitability of the Betz cell.The latency of the depression was a few msec and its duration of 50-100 msec.
3. Even such a weak stimulus as failed to fire the Betz cell could produce the depression.
4. The depression failed to appear following long lasting repetitive stimulation of the peduncle at a rate of 100/sec.
5. Subconvulsive doses of strychnine abolished the depression.
6. From these findings it was concluded that the depression represent recurrent inhibition of the Betz cell.

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The nervous control of the renal blood vessels were studied quantitatively in ‘spinal cord-renal nerve-kidney’ preparations of the toad following perfusion of its renal blood vessels with Ringer solution. The results obtained are summarized as follows.
1. When renal nerves were stimulated supraliminally electrically by square pulses, the rate of renal outflow decreased by about 90 per cent or more in ‘renal artery-renal vein system’ and by 33 per cent or less in ‘renal portal vein-renal vein system’. Dependence of the effect on each of the factors of the stimulating pulses (strength, duration and frequency) were studied separately and quantitatively. A vasoconstrictive substance could be detected in the perfusate of both system obtained during long lasting supraliminal stimulation of renal nerves. The effect of such perfusates tested on sino-atrial preparation of the toad was equivalent to 1.0μg/ml noradrenaline.
2. Renal nerves could be divided topographically into three groups. Each group innervates its own area of the renal vascular bed but there appears to be some overlapping.
3. Sectioning of the renal nerves produced an increase in the rate of outflow. Tonic discharges (1 to 4 impulses per second) could be recorded from the peripheral end of the nerves. These findings suggest a tonic innnervation through the renal nerves which contributes to renal vascular resistance.
4. Reflex vasoconstriction could be produced by the stimulation of the peripheral cut end of renal nerves in the ipsilateral side, but not in the contralateral.
5. The existence of vasodilator fibers in the renal blood vessels could not be demonstrated.Acetylcholine-like substance could not be detected in the perfusate obtained during stimulation of anterior root, posterior root and the vagus.

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By observing phrenic nerve discharges in dogs, the threshold P_CO2 (P_TCO2) for the respiratory system was examined during the course of passive hyperventilation lasting for 4-8 hours.
1. The degree of hyperventilation was so strong as to decrease alveolar P_CO2 to about 10mmHg.
2. The P_TCO2 was lowered with lapse of time of hyperventilation. The regression line for the relationship between arterial (P_TaCO2) and alveolar (P_TACO2) P_TCO2, and duration of hyperventilation in hour (H) were: P_TaCO2=-1.4H+29.3, and P_TACO2=-1.2H+28.7.
3. The regression line for relationship between arterial P_CO2 and plasma bicarbonate ([BHCO₃]) at the threshold condition was; P_TaCO2=1.4 [BHCO₃] _T+3.3.
4. In spite of decreasing the P_TCO2, arterial pH at the threshold condition was nearly kept constant.

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The effects of the repetitive stimuli and the temperature on the rising rate and the duration of action potential of the ureter smooth muscle of cat and guinea pig were studied with the aid of the intracellular potential recording technique. The recovery process of action potential in the ureter muscle of cat was examined. During the early relative refractory period, slow and small potential change as recorded. In the later phase, an action potential of a slow rising phase and of a decreased height was recorded. In guinea pig ureter, the action potential which was observed in the relative refractory period showed a slow rising rate, reduced oscillatory potentials and shortened duration. The rapid falling phase of the repolarization could be superimposable when the ureter muscle was repetitively stimulated. This finding resembled that found in vertebrate myocardium. The rate of rise of potential, the duration of action potential and the conduction velocity were decreased when the temperature of the bathing fluid was lowered.

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1. In the experiment on myofibrillar ATPase activity, the calcium at the concentration (3.0μM) corresponding to that contaminating the reaction mixture inhibited only slightly the relaxing activity of effective eluate. A far larger amount of calcium than that contaminating the reaction mixture was required a sufficient restoration of myofibrillar ATPase activity inhibited by effective eluate.
2. The inhibition-curve of the relaxing activity of effective eluate by the addition of calcium was similar to that in the case of EDTA or EDTA plus eluate. However, all the curves reached to their maximum at about 1.10^-4M calcium.
3. The decrease in myofibrillar ATPase activity or in tension of fibers was most 10% in the reaction mixture pretreated with Dowex A-1. The direct addition of Dowex A-1 having a sufficient binding capacity for calcium had a slight effect on the relaxation of glycerol-extracted muscle fibers.
4. The tension of glycerol-extracted muscle fibers, even in the system from which the free calcium was almost completely removed by the direct addition a sufficient amount of Dowex A-1, was remarkably decreased by the subsequent addition of microsomes, EDTA or EGTA.

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