1. The rod outer segments of the frog retinae were isolated following KIMURA'S flotation technique, and suspended in an NaHCO₃ free Ringer solution. The oxygen uptake by the rod outer segments of the frog retinae was measured by the Warburg apparatus.
2. Effects of various enzyme inhibitors were tested. It may be safely concluded that there are no dehydrogenase, flavin-enzymes or cytochrome c in rod outer segments.
3. The existence of cytochrome oxidase was denied in rod outer segments on assay.
4. Despite oxygen uptake, no liberation of CO₂ was demonstrated.
5. Analysis of metal inhibitors led to an assumption that molecular oxygen was eventually taken up by non heme iron.

View full abstract

It was shown that the extreme susceptibility to endotoxin after adrenalectomy in dogs seemed to be due to the intensification of hepatic responses to endotoxin. A complete depletion of liver glycogen together with a release of an endogenous “shock-inducing factor” was induced in the absence of glucocorticoids. This factor could be detected by passive transfer of the plasma of endotoxin-shocked adrenalectomized dogs. By inducing a hepatosplanchnic blood pooling it mainly determined the severity of the shock. It was non-dializable and heat-unstable. Glucocorticoid could prevent its release from the liver together with the glycogen depletion, but could not inhibit its action. Thus the mechanism of protection of endotoxin shock by glucocorticoid in adrenalectomized dogs was found to be due to the prevention of the induction of the hepatic responses. Once the responses were started it was hardly possible to check them by glucocorticoid. Thus the timing of the glucocorticoid administration was of prime importance in preventing the endotoxin shock. It was discussed that the prevention of liver glycogen depletion in response to endotoxin by glucocorticoid was not due to its so-called gluconeogenesis.

View full abstract

1. Neonatal rabbit blood exhibits a higher oxygen affinity than the maternal one and the difference gradually disappears as the postnatal age develops. The circumstance is also ascertained in the hemoglobin solution prepared from the fetal and maternal blood and the difference shows little alteration after the 20 hours' dialysis against deionized water in one and common vessel. No significant difference can be verified in the magnitude of heme-heme interaction between both kinds of hemoglobin irrespectively of their environments.
2. Minor but distinct differences are found between the fetal and adult oxyhemoglobins in the alkali denaturation behavior and the ultraviolet absorption spectrum and the dissimilarities disappear as the postnatal growth proceeds.
3. Starch-gel electrophoresis of both the adult and fetal carboxy-hemoglobins showed single homogeneous zone of the same mobility.
4. p-Chloromercuribenzoate titer per mole of the fetal oxy-hemoglobin is estimated as 2.2 and it increases gradually along with the postnatal development, reaching the figure of 3 or so in the adult ones.
5. These results are discussed in the light of previous investigations, and it is concluded that fetal and adult rabbit hemoglobin differ in physiological function as well as molecular structure. Contrary to human fetal and adult hemoglobins, the structural differences appear to be responsible for the distinction in the physiological function.

View full abstract

The fine innervation of the heart in dog and rabbit was investigated by the electron microscope. It was concluded that:
1. Not only precapillary but also true capillary in the area of sino-atrial node of dog and rabbit are innervated by cholinergic and adrenergic nerve fibers.
2. Two types of synaptic vesicles were identified, the one (cholinergic) has the average diameter of 500Å, while the other (adrenergic) 1, 000Å. The latter synaptic vesicles contain granules in the core. Dense granules in the core of the vesicles may be associated with catecholamine.
3. Possible role of the synaptic vesicles to the true capillary without muscular elements was discussed briefly.

View full abstract

For the purpose to establish a simple method for measuring N₂O gas the discharge light has been investigated under various conditions. Different from other gases it showed an intense after-glow, which appeared in a flowing sample at the distal portion of the discharge electrodes. The intensity of the after-glow has been measured by varying the vacuum pressure, the flow-rate, the concentration and the applied voltage. The intensity showed the maxi-mum at 3 mmHg when 1 Mc AC of 2, 000 volt was applied. For the flow-rate and the concentration the intensity increased hyperbolically not linearly respectively. However, at a concentration range lower than 30% it was fairly linear.
The after-glow was not influenced from other respiratory gases. Furthermore, the intensity was reproduced within 1% errors for the same concentration, and the response time was about 1 sec at the flow-rate of 30 ml/min. From the data obtained the after-glow seemed to be used for the continuous determination of N₂O concentration.

View full abstract

1. Some of the data obtained by HAGIWARA (1954) on the interval fluctuations of the sensory nerve impulse have been reanalysed with a modified model.
2. The modification consisted essentially of the introduction of a factor characterizing the rate of fluctuation of a random process that is thought to be super-imposed on the threshold of the impulse triggering mechanism.
3. The mean rate of change in amplitude of the step-wise defined random process was found to be in the order of a few hundred per second.
4. Some of the implications of the model: the time course of the random function immediately after an impulse, the large value of the noise intensity relative to the rheobase and, as a consequence, the predicted existence of spontaneous discharge, were discussed.

View full abstract

1. The influences of the activity of the amygdala, the anterior limb of the anterior commissure and the mesencephalic reticular formation of the activity of the olfactory bulb were studied in the rabbit by means of electrical stimulation.
2. A potential wave evoked by electrical stimulation of the olfactory epithelium (A-wave) was inhibited considerably and for as long as 600 to 800 msec, when the lateral part of the amygdala was stimulated. But this phenomenon was not observed when the medial part was stimulated.
3. The above inhibition was strikingly elongated when single or repetitive stimulation of the mesencephalic reticular formation was combined. However, the latter stimulation itself did not show any inhibitory effect upon the Awave.
4. From the shape of the evoked potential, the striking inhibitory phenomenon and the histological finding of the efferent fibers in the bulb, it was concluded that the lateral part of the amygdala sends inhibitory fibers to the olfactorybulb.
5. The centrifugal inhibitory fibers from the lateral part of the amygdala were traced to the olfactory bulb. They were found in parallel with and slightly above the lateral olfactory tract.
6. Any inhibitory effect was not found upon the A-wave when the anterior limb of the anterior commissure was stimulated singly or together with stimulation of the mesencephalic reticular formation.

View full abstract

Implantable pH glass electrode for continuous recording of blood pH in situ is described. The electrode was applied for telemetering of pH of circulating blood in running dogs.
Results obtained are as follows:
1. This pH glass electrode gave 58 mV per one pH change which almost satisfy Nernst's theoretical value.
2. The stability of the electrode was high (within 0.017 pH units over several hours) and the reproducibility was very good (±1.0 mV of standard deviation).
3. Response time of the electrode was fast enough to detect rapid change of blood pH.
4. Radiotelemetry of blood pH was attempted with this pH glass electrode by FM-AM system. The telemetry gave fairly stable and reasonable results.

View full abstract

1. Glass microelectrodes were inserted into the lateral vestibular nucleus of Deiters, and potential changes were recorded both extracellularly and intracellularly under stimulation of the spinal cord.
2. When the ipsilateral C₃ segment was stimulated at its ventrolateral surface, negative field potentials of several millivolts were recorded from the area which was histologically identified as Deiters' nucleus. These field potentials were presumed to be caused by the antidromic activation of Deiters' neurones through the vestibulospinal tract.
3. The antidromic field potential of Deiters' nucleus showed different distributions in the ventrodorsal direction for activation at the C₃ and L₁ levels, which is in keeping with the histologically determined somatotopical arrange-ment.
4. Within the nucleus of Deiters specified by the field potentials, a total of 134 units were impaled with microelectrode. They were identified as Deiters' neurones by the characteristics of the antidromic spikes, their afterhyperpolarization and by occurrence of synaptic noise and PSPs.
5. In sixteen selected neurones the resting potential was -55 to -75 mV and the spike height 60 to 100 mV (mean, 80.8 mV). The duration of the spike was 0.4 to 0.6 msec (mean, 0.47 msec).
6. The conduction velocity along the vestibulospinal fibres was determined in fifty Deiters' neurones which were activated antidromically both from the C₃ and L₁ segmental levels. It ranged from 24 to 140 m/sec, the peak frequency being at 90 to 100 m/sec.
7. The falling phase of the spike, after it crossed the base line, reversed to an afterhyperpolarization which reached its summit at 0.7 to 8.8 msec (mean, 2.4 msec), and diminished within 33 to 100 msec (mean, 49 msec). These values are smaller than those for cat spinal motoneurones. As a unique feature in Deiters' neurones the afterhyperpolarization did not show a temporal summation when it was evoked successively at short intervals.
8. The stimulation of the ipsilateral C₃ segment just subthreshold for the axon of the impaled cells induced EPSPs monosynaptically in 15.4% and IPSPs polysynaptically in 7.7% of the examined neurones. The recurrent axon collaterals might be responsible for these IPSPs, but the possibility was not excluded for the other pathways.
9. Stimulation at the C₃ segment supramaximal for the antidromic field potential of Deiters' nucleus produced monosynaptic EPSP in 50% and polysynaptic IPSP in 28.6%. It was suggested that the monosynaptic EPSP was produced through the ascending tract fibres in the spinal cord.
10. In view of the fast time course of the action potential and of rarity of the possible recurrent inhibition, it was postulated that Deiters' neurones would be grouped with the fast type of lumbosacral motoneurones.

View full abstract

1. The level of the notch or the step on the upstroke of the action potential recorded through a microelectrode from the rabbit atrioventricular node was not constant. The change of this part induced by changing the extracellular potassium or sodium concentration did not show any simple relationship.
2. Stimulation rate was increased in normal Tyrode solution, in solution with a higher potassium concentration and in Tyrode solution after addition of acetylcholine. Under all of these conditions the action potential was variously decomposed. The fragmentation was so marked that both of two mechanisms, i. e. local graded response and electrotonic spread of the action potential of adjacent muscle fibers, must be considered.
3. A peculiar finding occasionally observed in the atrioventricular node was mentioned. Only the chief part of the action potential showed a successive delay, the firing level changed successively, but the step part remained unchanged. This finding suggested more clearly that the nature of the small potentials here is the electrotonic spread of the action potential stopped by a small area of block or of refractory state and that the excitation waves made a detour to reach the site of exploration.
4. The reason why only the nodal potential shows special features under such conditions is probably due to the sparsity of muscle fibers in the atrioventricular node.
5. The above-mentioned mechanism refers to relatively abnormal states of the atrioventricular node in which its action potential is apt to show the steplike potential.

View full abstract