The effects of tonic and rhythmic contraction of the intestine on the arterial and venous blood flow through the intestinal segment were investigated in dogs.
Intestinal contractions always caused periodicity in the arterial and venous blood flow. The correlation between intestinal contraction and the arterial and venous flow was classified into three patterns; the contraction phase type, relaxation phase type and combination type were observed in tonic contraction, and the contraction phase type and relaxation phase type in rhythmic contraction.
In the contraction phase type, augmentation of venous flow and diminution of arterial flow was elicited during the contraction period. In the relaxation phase type, diminution of venous and arterial flow during the contraction period was followed by sustained augmentation of flow during the relaxation period. The combination of these two patterns is the combination type.
Augmentation of venous outflow during the contraction period was produced by expelling blood from the intestinal wall, as the arterial inflow was diminished during this period. Augmentation of arterial and venous flow during the relaxation period was caused by vasodilatation due to prolonged compression of the blood vessel by contraction of the intestinal musculature.

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A cardiotachometer has been devised to record the variation of the frequency of the sino-atrial node, but no apparatus has been reported which simultaneously records the frequency variations in atrioventricular conduction time and the sino-atrial node frequency. In an attempt to demonstrate how the sinus rhythm affects the A-V nodal conduction time, excitation conduction time between the right atrium and ventricle was recorded continuously by a newly devised A-V interval meter and compared with the variation in the length of the cardiac cycle (R-R interval).
In the post-operative unanesthetized dog, the respiratory variation in A-V interval was from 7 to 13 msec while the R-R interval ranged from 350 to 500msec. The variations of the A-V and R-R intervals were in phase under nervous control but out of phase with pacing and pharmacological intervention. Both variations diminished in amplitude when the dog stood up or ate, when propranolol was administered intravenously, or when atropine was given.
In the anesthetized animal right vagal stimulation caused an abrupt lengthening of the R-R interval after one second or less, while left vagal stimulation usually prolonged the A-V interval after more than one second. Stimulation of the left stellate ganglion resulted in a shorter A-V conduction time without a change in the R-R interval, while stimulation of the right stellate ganglion generally caused tachycardia.

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Stress relaxation tests and stress-strain hysteresis tests were carried out on longitudinal and circumferential strips excised from various portions of the aorta and from the external iliac and femoral arteries. In order to investigate the results from the architectural point of view, both tests were also carried out on the nuchal ligament, tendon and intestinal smooth muscle bundle which are composed mainly of elastin, collagen and smooth muscle fiber, respectively.
1. A very good positive correlation was found between the relaxation strength at 1 second and that at 300 seconds after stretch, regardless of the cut-out region and direction of the strips.
2. An exponential relationship was obtained between the plastic deformation rate and the relaxation strength at 300 seconds after stretch.
3. Stress-strain curves obtained from every portion of the arterial tree were concave toward the stress axis.
4. The direction-dependent difference in mechanical behaviors was not significant in the proximal part of the aorta. Below the distal thoracic aorta, on the other hand, the more peripheral the portion, the more the circumferential and the less the longitudinal contribution of the viscous element.
5. The nuchal ligament was regarded as almost entirely elastic, whereas the intestinal smooth muscle showed remarkable viscoelasticity. For these two tissues, plots representing the relationship between plastic deformation rate and relaxation strength at 300 seconds were situated on the extrapolated parts of the regression curve which showed the relationship for aortic and arterial strips. The tendon was characterized by an extremely high Young's modulus which was several thousand times greater than that of the former two tissues. The average modulus of the arterial walls was between that of the nuchal ligament and of the smooth muscle bundle.
6. Architectural arrangements of elastin, smooth muscle and collagen in different portions of the arterial tree were discussed on the basis of mechanical properties of the nuchal ligament, intestinal smooth muscle and tendon.

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1. The membrane properties of canine papillary muscle were investigated using a sucrose gap and glass microelectrodes.
2. Replacement of chloride by large anions had little effect on the resting potential but reduced the resting membrane conductance by 30%. It was suggested that the chloride permeability remained almost unchanged when the membrane was hyperpolarized.
3. When a constant hyperpolarizing current was passed across the membrane, the membrane conductance fell slowly to a certain level, and returned to its initial level in a few seconds after the end of the current.
4. Similar changes in conductance during hyperpolarization were also observed in chloride-deficient or sodium-deficient solution.
5. Conditioning hyperpolarization greatly affected the magnitude and the time course of the electrotonic potential produced by the second pulse of hyperpolarizing current, whereas conditioning depolarization had little effect.
6. The region of high resistance in the current-voltage relation extended to more negative potentials in 1.34mm [K] ₀ than in 2.68mm [K] ₀.
7. The current-voltage relations both in 0.27mm [K] ₀ and in glycerolhypertonic solution showed persistently high resistance at any membrane potential investigated (from-50mV to-150mV). The slow potential change during hyperpolarization disappeared in these solutions.
8. The results are interpreted as indicating that:
(a) A delayed rectifier system for potassium current exists in the potential region more negative than the resting potential.
(b) The potassium permeability of canine papillary muscle rises when potassium ions move inward across the membrane and falls when they move outward (anomalous rectification).

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The physiological properties of afferent impulses which were recorded from the distal cut end of lumbosacral ventral roots of the cat were investigated by applying weak natural stimuli to the hindlimb. These afferent impulses were considered to arise from the sensory fibers originating from aberrant cells in the ventral roots and mixed nerves (beyond the point of dorsal/ventral root separation). Of 29 sensory fibers recorded from the 7 L₇, 13 S₁ and 1 S₂ ventral roots, 6 fibers were from muscle spindle, 8 fibers innervated the skin, 7 fibers responded to joint movement, 1 fiber showed discharges associated with movement of the experimental table and 1 fiber responded to both mechanical and temperature stimulation. The receptive fields of 6 fibers were not determined by the stimulus modalities employed. The properties of the sensory receptors which are innervated by these aberrant sensory fibers were similar to those innervated by the dorsal root afferent fibers.

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1. An intracellular recording technique was used to record excitatory postsynaptic potentials (EPSP's) from the eighth nerve fibers of goldfish. EPSP's were evoked by applying sound stimulus, and spontaneous miniature EPSP's were also observed.
2. Even when the stimulus sound was kept at a fixed intensity level, the EPSP amplitude showed some fluctuations including occasional failures of the response.
3. The applicability of Poisson's law was tested for several intensity levels of sound stimulus in the same fibers. The Poisson relation was found applicable to the amplitude distribution of EPSP's evoked by a weak sound, but some discrepancies were found for a strong sound.
4. It was concluded that the transmission between hair cells and primary eighth nerve fibers of goldfish occurred in quantal steps. Some theoretical implications of the present results were discussed.

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Studies were made to clarify the nature of the coupling potentials which are produced, beside the EPSP's, in the eighth nerve fibers of goldfish in response to the sound stimulus. Analysis was made by studying semiquantitatively changes in the size of the coupling potentials, the EPSP's, and the microphonics upon changing the sound intensity; that is, an input-output relationship at the synapse between hair cells and eighth nerve fibers was studied. Results obtained are as follows:
1. The coupling potentials were produced without any delay after the initiation of the microphonic deflections and their time course was similar to that of the latter. Also the amplitude of these two potentials was changed in parallel upon changing the intensity of the sound stimulus.
2. EPSP's were produced with a definite delay after the initiation of the microphonics and their amplitude increased more steeply than the microphonics upon increasing the sound intensity. A 10dB increase in the sound intensity produced, in the exponential range, from 4- to 20-fold increase in the EPSP size.
3. The coupling potentials, like the microphonics, showed a greater resistance to cooling and anoxia.
4. It was concluded that the coupling potentials are quite different in nature from the EPSP's. While the EPSP's were generated in response to a released transmitter, the coupling potentials seem to have been produced in a more direct relationship with the microphonics.

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1) Chemoreception was investigated of the receptor end organ on the flank skin in several fresh water and sea water bony fish by recording the electrical responses in single fibers of the lateral-line nerve (X) and of the accessory lateral-line nerve (VII). Three species of fish, catfish (Ictalurus), mullet (Mugil) and carp (Cyprinus) were studied extensively.
2) Responses of the receptor organ to monovalent cations, K⁺, Na⁺, Rb⁺, NH₄⁺, Li⁺, and Cs⁺ in the solution were observed on all fishes studied. Among them K⁺ had the strongest effect. Inorganic anions were ineffective. In fresh water fish the sensitivity of the end organ was much superior to that of marine fish. The responses to various concentrations of Na⁺ were almost parallel to responses to K⁺, although somewhat smaller in fresh water fish, while in marine fish the sensitivity to Na⁺ was much inferior to that to K⁺. Such a fact may come from an abundance of Na+ in the environment. In those end organs divalent cations like Ca⁺⁺, Mg⁺⁺ and Sr⁺⁺ suppressed excitatory effects of monovalent cations when the former were applied simultaneously or in sequence to the end organ. Tetrodotoxin also produced a similar effect. Such suppressive effects were reversible. After rinsing the end organ with fresh water or sea water thoroughly, those effects subsided completely.
3) In euryhaline fish when they move from sea water to fresh water or vice versa, the sensitivity to K⁺ and Na⁺ changes within a certain period of time from the type of marine fish to that of fresh water fish or in the opposite direction. In a mullet the complete change of sensitivity of the end organ occurred in 7 days.
4) In the case of catfish there were observed a variety of responses to chemical stimuli, not only to monovalent cations but also to divalent ones and several others as well. Some fibers were very sensitive to NH₄⁺, or specifically to quinine or glutamate. None of them responded to sugar.
5) Histological studies have disclosed that
(a) the catfish has various types of end organs innervated by the lateral line nerve and the accessory lateral-line nerve on the flank skin; canal neuromasts, large and small pit organs and many terminal buds.
(b) The mullet has 12 or 13 rows of the lateral-line organs on the flank skin. The scale along each lateral-line has a groove at its central part and a single neuromast is located in it. Through a small hole a few lateral-line nerve fibers reach to the end organ. Each groove is discrete and independent so that there is no lateral-line canal. From such structure of the lateral-line system the end organs in grooves are thought to be free neuromasts.
(c) On the flank skin of the carp there are free neuromasts and terminal buds as well as canal neuromasts. The terminal buds, however, are not as numerous as in the catfish.

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