The neurons responding to the mandibular muscle deformation were explored in the supratrigeminal nucleus region above the trigeminal motor nucleus, and the response pattern of these neurons were analyzed.
1. All of the neurons in the supratrigeminal nucleus showed a background activity, and it means that steady impulses f rom the jaw muscles flow into this nucleus. Def ormation of the muscle spindle of the jaw closing muscles activated these background activities.
2. In the supratrigeminal nucleus three different types of interneurons which responded to the Ia afferents from the jaw closing muscles were clearly identified. The first type of cell is the M-Cell which responded only to the mechanical deformation of the masseter muscle, the second is the T-Cell, which responded only to the temporalis muscle. The third cell is the M·TCell which is the fundamental cells in the nucleus and responded to both the masseter and temporalis muscles.
3. The M · T-Cell showed the summated response when the masseter and temporalis muscles were stimulated at the same time. These interneurons were not affected at all by afferent impulses from the antagonistic muscle. Fifty-six cells out of explored 58 cells in the nucleus were identified as the M · T-Cell, and one M-Cell and one T-Cell were identified, respectively. The M · T-Cell with the activity coefficient A_k=1 is the fundamental cells in this nucleus.

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In the first phase of this investigation adult, male Sprague-Dawley rats were maintained under rigidly standardized environmental conditions which included an artificial light-dark cycle (light from 0600 to 1800). During two separate 24-hr periods subgroups of rats were removed from the colony room every hour or. the hour and a cardiac tap was performed on each rat subsequent to sodium pentobarbital anesthesia, Inorganic sulfur and phosphorus determinations were made on the plasma obtained from these rats. The pattern of fluctuation in both compounds over the 24-hr period indicated that both had a circadian component with essentially the same phasing. The crest in the level of both compounds occurred between 1300 and 1600, the trough values for inorganic phosphorus occurred between 0300 and 0600, for the inorganic sulfur it occurred at about 2200.
Similar studies were made on starved, blinded, and also on rats subjected to prolonged periods of continuous illumination. The inorganic phosphorus rhythms persisted in starved animals, inorganic sulfur was not determined on starved animals.
The rhythms of both compounds persisted with altered phasing in blinded animals. The rhythms seen in blinded animals were somewhat flattened and had a tendency to be irregular when compared to animals kept in a light-dark cycle. Both the inorganic sulfur and phosphorus levels were significantly lower in blinded animals when compared to animals subjected to a light-dark cycle or to continuous illumination.
In those rats subjected to continuous illumination the general tendency was for the inorganic sulfur rhythm to flatten out. The inorganic phosphorus rhythm persisted under this environmental condition but the profile was radically altered.
Evidence is presented to indicate that the ability of the organism to respond to a potentially lethal dose of a drug depends on the time of day the drug is administered. When an identical dose, based on body weight, of strychnine was given to subgroups of rats at different time points along a single 24-hr time scale as many as 85% died at one time of day whereas only 35% died at another time of day.
Evidence also is presented to indicate that the ability of the rat to survive a cardiac tap while under a therapeutic dose of sodium pentobarbital may depend on the time of day the cardiac tap is performed. The importance of recognizing the time structure of the living organisms is discussed.

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Using the partition chamber method together with microelectrodes, membrane constants of the dog heart were determined in the pectinate muscle of the right atrium (A), false tendon (F) and papillary muscle of the right ventricle (V). The membrane capacity calculated from the time course of propagating action potential foot and propagation velocity was 2.6, 1.7 (6.8) and 0.6μEF/cm² for A, F and V. The electrotonic potential and its spatial decline observed with the partition chamber conformed with the cable law. The space constant was 1.24mm for A, 1.25mm for F and 1.18mm for V. The time constants were 14.6, 15.0 and 3.2msec. The membrane resistance calculated from these values appeared about 5600, 8900 (2200) and 5300Ωcm² for A, F and V respectively. The safety factor for excitation conduction was estimated to be 4.4, 7.6 and 2.0. Differences and agreements in value between the membrane constants determined by mass polarization and by intracellular polarization were discussed.

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It was shown that frog's ventricle respond with multiple firing accompanied by a long continued contraction in response to a single direct electrical stimulus when the concentration of Ca⁺⁺ in the bathing Ringer's solution is raised up to about 8 times the normal concentration. This was shown to be due to the effect of excess Ca⁺⁺ to localize the response by partial blocking, while a possibility of spreading the excitation to the whole ventricle still remains. The localization of the response was prevented by excess K⁺, epinephrine and by low temperatures. The spread of excitation was completely blocked by procaine or tetrodotoxin. All these conditions were found to inhibit the multiple firing accompanying a long sustained contraction, which is estimated due to an increase of Ca content in the ventricular tissue (a net gain). The net gain in the ventricular Ca content was found to be due to the result of multiple firing of the ventricle.

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Some properties of the relaxing factor systems and the calcium sensitivity of myofibrils prepared from rabbit red muscle were studied with the following results.
1. The mixed myofibrillar ATPase activity was inhibited by the microsomal fraction and the effective eluate prepared from red muscle by about 60 and 40%, respectively. These relaxing activities were removed by caffeine depending on the concentrations.
2. The supernatants prepared from red muscle homogenates inhibited the mixed myofibrillar ATPase activity by about 15% at the 10 vol.%.
3. Five mM azide did not affect the calcium uptake of the red microsomal fraction or the inhibitory effect of the red mitochondrial fraction on the mixed myofibrillar ATPase activity.
4. Over the range of pCa from 7.9 to 5.2, the ATPase activities of red and white myofibrils increased with decreasing pCa and reached a maximum at pCa 5.5. The maximum ATPase activity of red myofibrils was about one fourth that of the white ones. The ATPase activity of white myofibrils was more remarkably activated than that of red myofibrils by decreasing pCa at lower than 6.5.
5. The ATPase activity of red myofibrils was less inhibited by EGTA than that of white ones; for 50% inhibition, 30 μM EGTA was required in red myofibrils and 10 μM in white ones. In the presence of 5 mM azide, the inhibitory effect of EGTA on red myofibrils increased only about 15%.
6. There was no difference in the calcium contents between red myofibrils and white ones.
On the basis of these results, the relaxation mechanism of living red muscle was discussed.

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1. Both the rate and the amount of calcium uptake by the reticulum isolated from frog skeletal muscle were dependent on temperature. The activation energy of calcium uptake was about 3, 600cal/mole. A portion of calcium taken up by the reticulum at 20°C was released reversibly by cooling; about 20 and 50mμ moles Ca/mg protein by cooling to 10 and 0°C, respectively.
2. Ten mM caffeine did inhibit the calcium uptake of the reticulum at 20 and 10°C. The inhibitory action of caffeine at 10°C was slightly more remarkable than that at 20°C. It was noted that the calcium uptake at 0°C was not affected by 10mM caffeine.
3. At 20°C, about 20-25mμ moles Ca/mg protein was released from the reticulum by the addition of 1-2mM caffeine. The calcium release induced by 1mM caffeine was only slightly potentiated by cooling from 20 to 10°C. On the other hand, the calcium release by cooling from 20 to 0°C was the same with or without 2mM caffeine present.
4. The calcium taken up by the reticulum at 0°C was only a little released by the addition of 10mM caffeine.
5. The myofibrillar ATPase activity and its Ca-sensitivity were dependent on temperature. The maximal ATPase activity of myofibrils at 10 and 0°C was only about 40 and 6% of that at 20°C, respectively. And the added Ca⁺⁺ concentration required for half-maximal ATPase activity was about 35μM at 20°C and about 100μM at 10°C, respectively.
6. These results were discussed in relation to the mechanism of rapid cooling contracture in caffeinized frog muscle fiber.

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1. The efflux and uptake of Ca in Mytilus ABRM at rest and during potassium contracture were examined by use of ⁴⁵Ca.
2. The Ca efflux during potassium contracture was 0.162 p-mol/cm². sec. and increased to about 6 times that of the resting state.
3. The resting influx of Ca was 0.028 p-mole/cm². sec. The increase of Ca uptake during potassium contracture in 2 min was 0.145μ mol/g wet wt. muscle and the Ca influx during the activity was 0.258 p-mol/cm². sec. Therefore the Ca influx during potassium contracture increased about 9 times that of the resting state.
4. The activation of the contraction of Mytilus ABRM was discussed on the basis of these results and other physiological properties. It was suggested that the initiation of contraction of Mytilus ABRM may be associated with Ca entry from the extracellular space.

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1. Applying the electrical stimulation on the isolated neurohypophysis of the rat, the oxytocin release was bioassayed and the compound action potential was recorded.
2. The repetitive pulse stimulation at the optimal frequency (about 20 Hz) was more effective on the oxytocin release than the excess K⁺ stimulation to the gland.
3. Two waves were separated in the compound action potential traveling along the stalk evoked by a single shock. The conduction velocity of the first wave was 1.64±0.26m/sec and that of the second wave was 0.69±0.17m/sec.
4. While a marked decrease in the size of the action potential was observed, the output of oxytocin was not declined by the repetitive stimulation at 10Hz or 20Hz.
5. The relation between the electrical activity and the secretory mechanism was discussed, and it is suggested that the depolarization at the nerve terminal may be directly linked to the secretory activity.

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1. The effects of divalent cations (Ca⁺⁺, Mg⁺⁺, Sr⁺⁺ and Ba⁺⁺) on the frequency of miniature end-plate potentials (m. e. p. p. s) in the amphibian neuromuscularjunction were investigated intracellularly in the presence of 2 to 8% ethanol
2. The frequency of m. e. p. p. s was increased when the concentration of calcium ion was raised in ethanol-Ringer's solution and magnesium ion acted as an antagonist to calcium ion.
3. The frequency of m. e. p. p. s was also increased by strontium and barium ions in the presence of ethanol and magnesium ions acted as an antagonist to these ions. The effect of barium ion was exerted in concentrated ethanol (4% or more).
4. In the spontaneous transmitter release, calcium and strontium ions competed with magnesium ion on a one-to-one basis and barium ion competed with magnesium ion on a one-to-several (4 to 8) basis.

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Constant pressure perfusion of the sinus node artery at 100 mmHg was arranged in vagotomized dog heart in situ and adrenergic receptor mechanism of the sinus node artery was studied. Vasoconstrictor and/or dilator responses were obtained when naturally occurring catecholamines, i. e., dopamine, norepinephrine and epinephrine were given intra-arterially. Response to isoproterenol was exclusively vasodilatation. The vasodilator response to the catecholamines was prevented by propranolol, one of the adrenergic blocking agents, while the vasoconstrictor response was abolished by injection of alpha-adrenergic blocking agent, phentolamine or phenoxybenzamine, selectively into the sinus node artery.
It was concluded that the existence of both alpha- and beta-adrenergic receptors even in the sinus node artery which is functionally different from the ordinary myocardial arteries.

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Thirty boys and twenty six girls of almost standard stature and body weight in junior and senior high schools were tested on a bicycle ergometer with the stepwisely increased loading. Maximal oxygen uptake was measured as related to age and sex. For the practical use, some physiological parameters and predicted value of maximal oxygen uptake from submaximal work were examined. The following results were obtained:
1. Mean values of measurements in the subjects were as follows:
male age 12-13 14-15 16-17 number 10 10 10 stature (cm) 149.6±5.6 160.5±4.0 166.2±1.3 weight (kg) 39.6±3.7 50.0±4.4 56.8±1.5 max Vo₂ (1/min) 1.62±0.24 2.09±0.29 2.41±0.32 max Vo₂ (ml/min/kg) 40.7±3.9 42.0±6.7 37.7±5.6 female number 10 10 6 stature (cm) 150, 0±2.0 154.3±1.5 154.8±0.5 weight (kg) 41.3±3.1 47.9±2.1 51.0±2.0 max Vo₂ (1/min) 1.44±+0.15 1.39±0.12 1.37±0.15 max Vo₂ (ml/min/kg) 34.9±3.6 28.9±2.6 26.7±3.3
2. Maximal oxygen uptake increased in advance of age in the males, but slightly decreased in females. Maximal oxygen uptake per body weight showed a peak at 14-15 years in males, but it decreased with the age in females.
3. Maximal performance, maximal oxygen pulse, maximal oxygen pulse per body weight were significantly correlated to maximal oxygen uptake per body weight. They may have physiological significance in themselves, but they are not so feasible as to be used for a practical substitute for the maximal oxygen uptake.
4. Response of heart rate to a given load, that is, predicted maximal oxygen uptake with ÅSTRAND-RYHMING nomogram, PWC₁₇₀/kg and fitness index of the Step Test (Modified Harvard Step Test adopted by the Ministry of Education, Japan) had no significant correlation to maximal oxygen uptake. The invalidity of the former two measurements was derived from the lack of a steady state due to stepwise loading in every two minutes. The latter test was considered to be too weakly loaded.
5. Stepwisely increased loading method, every two minutes on a bicycle ergometer, is adequate for the measurement of direct maximal oxygen uptake, but in this procedure no practical parameters including indirect predicting method with ÅSTRAND-RYHMING nomogram can be substituted for maximal oxygen uptake.

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1. The active transport in Na-rich SOL and EDL muscles of K-deficient rats was studied by soaking the muscles in 10mM-K fluid with or without various agents at 30°C or at various temperatures for 2 hr.
2. The active transport in Na-rich muscles of K-deficient rats after recovery was greater than that of normal rats, made Na-rich by soaking the muscles in cold K-free fluid for 2hr. Na extrusion and K uptake in Na-rich SOL muscles of K-deficient rats during recovery were greater than those in EDL muscles.
3. Na extrusion in Na-rich EDL muscles during recovery was fully inhibited at temperature ranging from 1 to 11°C, while K uptake was inhibited partially at 11°C.
4. The rate constant of Na extrusion during a recovery period of 0-30min were 2.19hr^-1 in SOL muscles and 2.15hr^-1 in EDL ones.
5. The Na-K exchange in Na-rich muscles of K-deficient rats does not appea to occur on a simple one-to-one basis.
6. Addition of ouabain (0.001mM), IAA (0.2mM) and FDNB (0.03mM) to the recovery fluid produced marked inhibition on the active transport in Na-rich SOL muscles. Presence of aspartate ion facilitated the active transport, but pyruvate and glutamate ions had no effect.
7. Acetylcholine (8μg/ml) increased the active transport in Na-rich EDL muscles during recovery, whereas succinylcholine (2μg/ml) inhibited it. Little effect by tubocurarine (3μg/ml) was observed.
8. FDNB (0.005mM)-treated Na-rich SOL muscles showed the action potential of a smaller amplitude and of a longer duration. Tetrodotoxin (0.08μg/ml) abolished the action potential of Na-rich EDL muscles and produced delayed rectification by a strong cathodal current.

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The intestinal motility induced by occlusion of the cranial mesenteric artery was studied on unanesthetized spinal dogs.
1. An increase in intestinal motility and tone occurred most frequently (in 23 out of 32 observations) in the initial phase of arterial occlusion, while a decrease occurred less frequently (in 2 out of 32 observations).
2. This increase in intestinal motility and tone was abolished by tetrodotoxin and atropine, suppressed by pentobarbital, potentiated by physostigmine, and remained unchanged with vagotomy or hexamethonium.
3. From these results it is suggested that the release of acetylcholine through excitation of the intramural cholinergic neurons due to oxygen lack or an increase in CO₂ during arterial occlusion is responsible for the increased intestinal motility.
4. It is discussed concerning a possible mechanism operating in the decreased intestinal motility by arterial occlusion.

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