The effects of several heavy metal salts on the carp palatal chemoreceptors were studied by applying the metal salts externally to the taste sensitive area of the palatal organ while recording the electrical responses from the palatine nerve innervating the organ.
Treatments of the organ with low concentrations of Na₂PtCl₆, NaAuBr₄, NaAuCl₄, HgCl₂, and TlCl₃ for a short period depressed the response to sucrose. The response to sodium chloride was not affected or occasionally enhanced slightly by these metal salts. CuSO₄, ZnSO₄, AgNO₃, and UO₂ (CH₃COO) ₂ tended to depress both the responses to sucrose and sodium chloride simultaneously. The gold depression of the sugar receptor increased with rising concentration of NaAuCl₄ and was recovered by cysteine. These results suggest that the reaction of the receptor with the chloraurate does take place at the receptor membrane, perhaps at the receptor site.
N-ethylmaleimide and iodoacetate depressed non-selectively the responses to sucrose and sodium chloride. Histidine, though more weakly than cysteine, could recover the gold depression of the sugar receptor. These data, along with the non-selective depression by the above metals, suggested participation of some reactive groups other than the sulfhydryls in the reaction of the receptor membrane with gold ions, while some of the above mentioned data suggests an involvement of -SH groups in the reaction of the receptor.

View full abstract

The effects of Ba ion on the electrical activity of the guinea-pig antral smooth muscle were investigated with the double sucrose gap method.
1. Ba ion in the presence or absence of Na ion depolarized the membrane and increased the input resistance of the membrane.
2. The spontaneously generated spike was followed by a sustained depolar ization (plateau formation) which lasted more than one minute. Transitions of the membrane potential between the two levels (rest and plateau) appeared periodically.
3. The duration of the plateau depended on the membrane potential level.
4. The plateau formation required Na ion, since when Na ion was replaced with tris, chorine or sucrose, the spike but no plateau formation was observed.
5. Ba ion generated the spikes with plateaus in various concentrations of K ion (0.59-17.7 mM). With more than 29.5 mM K ion, the membrane was further depolarized and oscillatory spikes or depolarization block of the spike occurred.
6. Ba ion also produced the spike and plateau in solutions containing foreign anions.
7. The results led to the conclusion that Ba ion mainly inhibits the K-con ductance during the resting state, carries the current and delays the onset in K-conductance increase during the active state of the membrane.

View full abstract

1. The electrical properties of the longitudinal muscle of the guinea-pig fundus were investigated with the microelectrode method.
2. The membrane potential was -58.1 mV, the space constant of the membrane was 2.2 mm and the time constant of the membrane was 130 msec. The cable equations could be applied to this tissue.
3. When the current-voltage relation was observed by applications of weak inward and outward current pulses, the rectifying property of the membrane was observed.
4. Application of strong intensity of inward current pulses to the membrane produced an electrotonic potential with an initial transient phase which was gradually reduced in amplitude to a steady level. Application of outward. current pulses to the membrane produced an electrotonic potential which gradually increased in amplitude to a steady level.
5. Decrease and increase in amplitude of the electrotonic potential during application of strong inward and outward current pulses was mainly due to increased and decreased K-conductance of the membrane respectively, since the above effects were not influenced by either Na-free (tris) Krebs or NO₃- and C₆H₅SO₃- Krebs solution.
6. A spike of ‘all or none’ type could not be recorded from all muscle fibres but abortive spikes could often be recorded. Some of the muscle fibres did not produce an active response.
7. On treatment with TEA (3-5 mM), the rectifying property of the membrane was suppressed, and the generated spike was the ‘all or none’ type. The rate of rise of the spike was not affected, but the rate of fall of the spike was markedly reduced.
8. The conduction of excitation from the fundus to the pylorus was often incomplete. On treatment with TEA, conduction of the excitation was not decremental.
9. The physiological roles of the fundus of the stomach was discussed in relation to the properties of the muscle membrane.

View full abstract

1. The relationship between electrical and mechanical properties of the antrum circular muscle of the guinea-pig stomach in various ionic environments was investigated by the double sucrose gap method.
2. The minimum latency was 82 msec for the onset of the contraction after the spike showed the maximum velocity of the upstroke at 38°C.
3. The slow wave, the depolarization of the membrane by excess K ion, and the electrotonic potential also produced contraction.
4. On replacement of Na ion by other substances (Li ion, tris ion and sucrose), the amplitude of the spike was similar to that elicited in the presence of Na ion. The amplitude of contraction was not reduced by tris ion, but it was reduced by sucrose and Li ion.
5. NO₃ and Br ion lowered the electrical and mechanical threshold, and repetitive or enlarged spikes were evoked. The membrane resistance was reduced and the membrane was hyperpolarized. The contraction was enlarged in amplitude and prolonged in duration. Br ion showed more dominant effects on the electrical and mechanical activity than NO3 ion.
6. In the absence of Ca ion, Sr and Ba ion produced a spike with amplitude similar to that in the presence of Ca ion. However, the contraction was reduced in amplitude to a tenth of that in Krebs. When Cl ion was replaced with either NO₃ or Br ion, the amplitude of contraction was restored to more than half of the control.
7. The results are discussed in comparison with the properties of skeletal muscle, and it is proposed that the Ca ion which flows into the cells as the current carrier may release at least a portion of the Ca ion bound in the membrane and activate the contractile protein. Mobilization of bound Ca ion might be influenced by Na and Cl ion.

View full abstract

The skin potential level (SPL) and skin potential response (SPR) on the palmar surface of the finger and on the dorsal hand were studied on 15 male students during normal sleep.
The SPL on the finger, which was always negative during waking, was found to be closely correlated with the stages of sleep, the grade of decrease in negativity of the SPL reflecting the depth of sleep. This was not observed for the dorsal hand. Therefore the, finger SPL is a significant indicator of the depth of sleep as well as of the awake-sleep differentiation. The SPL regional differences were also recognized.
SPR rates for both sites were found to be significantly correlated with EEG phases during sleep, with maximal rate during slow wave sleep and a relative decrease during para-sleep. The SPR rate on dorsal hand was higher than that on the finger. For the dorsal hand positive SPR occurred, while negative SPR was seen exclusively on the finger. The amplitude of SPR seems to have no correlation with any of the sleep variables.

View full abstract

1. In isolated cortical slabs, intracellular recording was performed. The average membrane potential of impaled cells was -30 mV with a S. D. of ±7.0 mV. In these cells there were spontaneous postsynaptic potentials or synaptic noise, which were mostly solitary PSPs. The frequency of PSPs amounted to about 40% of that of the intact visual cortex.
2. Spontaneous IPSPs appeared more frequently in an isolated slab than in, an intact cortex. Inhibitory as well as excitatory interneurons were found in isolated cortical slabs.
3. By application of tetrodotoxin in an intact cortex, the spontaneous PSPs, disappeared within first 20 minutes, while in this period the membrane potential was largely depolarized.
4. Epicortical stimulation of an isolated cortex produces a long lasting IPSP as in an intact cortex. The mean latency of IPSPs was 2.8 msec with or without a preceding spike. No IPSP was elicited earlier than 1.7 msec. It was concluded that the intracortically produced IPSP was caused bi-synaptically by an inhibitory interneuron which might be connected with recurrent collaterals of cortical pyramidal cells.

View full abstract

Studies were made of effects of changing ionic composition of the medium, on the uptake of phenol red by goldfish kidney tissues. Most striking immediate effects were observed when medium Na⁺ concentration was varied. At a fixed Na⁺ concentration, the uptake curve for phenol red was composed of two components; one linear with the dye concentration and the other obeying Michaelis-Menten kinetics. The latter was absolutely dependent on the presence of Na⁺ in the medium, and a graded reduction of Na⁺ concentration resulted in a graded increase in the apparent Km for phenol red without changing the V_max. The apparent Km was a function of the reciprocal of the square of Na⁺ concentration, suggesting the presence of carrier activation by 2 Na⁺ Li+ had the similar but very small effect, but choline⁺ and K⁺ had no activating effect in the absence of Na⁺. In the presence of Na⁺, other monovalent cations showed an augmenting effect on the Na⁺-dependent uptake of the dye. The uptake in K⁺-free medium did not differ from that in the basic medium until 60 min, thereafter a strong depression was observed. Results of experiments on inhibition by PAH suggest that Na⁺-dependent carrier process for phenol red may exist at the peritubular border of the tubular cells.

View full abstract

1. The effects of electrotonic currents on afferent nerve fibers isolated from the frog sartorius muscles were examined.
2. The spontaneous discharges were facilitated by catelectrotonus, and depressed by anelectrotonus. The frequency and adaptation of the facilitated discharges during catelectrotonus were lower and slower when a particular current was applied in the vicinity of the capsule than when applied to an axonal portion distant from the capsule.
3. Current-frequency relation curves obtained with different resting muscle lengths were always in parallel with those obtained in situ length, with certain difference of the frequency caused by the change in the muscle length.
4. The static component in discharges during stretch of the muscle at 7 mm/ sec from an initial length was also increased with catelectrotonic and decreased with anelectrotonic currents respectively, but the peak frequency in discharge at completion of the muscle stretch appeared independent of the amount of electrotonic currents applied. Consequently the dynamic component was de creased under catelectrotonus and increased under anelectrotonus.
5. After the axon was crushed at a portion close to the capsule, all the spontaneous conducting discharges were abolished, and a single or few con ducting spikes could be elicited by the electrotonic currents.
6. The discharge of abortive spikes was increased or decreased by catelectro tonic or anelectrotonic currents of about ten times greater intensity than that for affecting the propagated spike.
7. The above results suggest that the axonal portion distal to the ramifying node possesses an ability for producing long-lasting discharges, and that the ability is due to a slow adaptation of the sensory terminal membrane which differs from that of the stem axon.

View full abstract

1. Investigations were made on the nervous system of Onchidium verruculatum, pulmonate mollusc. A microelectrode was inserted into the soma of the giant neuron on the dorsal surface of the perioesophageal ganglion complex in order to record the change in membrane potential.
2. Peripheral nerve trunks were stimulated electrically through bipolar electrodes. Each peripheral stimulus evoked the change in the membrane potential which were averaged by the digital computer, LINC-8.
3. The analysis of the averaged responses could disclose the modes of synaptic connections, including a direct connection; i. e. an axon or an axonal branch.
4. On the basis of the averaged responses, neuronal connections were deduced between peripheral nerve trunks and ganglion cells which could be always identified under a binocular microscope.
5. The possibility and the limitation of the averaging technique are discussed.

View full abstract

The experiments were performed on paralyzed (Flaxedil) cats under artificial respiration. The animals have been received a single dose of nembutal (30 mg/kg I. P.) in order to perform the surgical procedures. The reflex responses of the greater splanchnic nerve trunk, evoked by vibrational stimulation of the limbs were analyzed and compared with those elicited by electrical stimulation of afferent nerves.
The vibrational stimulation applied to the wrist of foot produced in the afferent nerves (radial, medianus, peroneus superficialis) was a long lasting discharge, while the corresponding response recorded in the splanchnic nerve was brief (FIG. 2). This sympathetic reflex response appeared exclusively when the vibration was applied to the limbs ipsilateral to the splanchnic nerve recorded.
The latency elapsing between the peak of the “first” response in the radial nerve and the peak of the “first” spike of the corresponding splanchnic response was of the order of 8-13 msec. The amplitude of the sympathetic reflex response increased when the strength of the stimuli augmented. For a given strength the repetitive vibrational stimuli (from 5-15/sec) produced a marked decrease in the sympathetic discharges.
When the radial nerve was electrically stimulated (suprathreshold) through the same pair of electrodes from which the radial nerve responses to the vibrational stimulation had been previously recorded, a splanchnic response similar to that obtained with the vibrational stimulation was observed. The excitability recovery curve to the vibrational stimuli and to the electrical stimulation was similar.
The splanchnic response that was produced either by vibrational stimuli applied to the limbs or by electrical stimulation of the afferent limb nerve fibers (with an intensity less than maximal) was called “first” splanchnic response because there was another efferent response (“second”) which appeared 40-100 msec after the stimulation. The “second” response was only produced when the strength of the stimuli was substantially higher than that needed for evoking the “first” splanchnic response. The “first” response had an ipsilateral and segmental character (confined to several spinal cord segments). The “second” response could be produced by the stimulation of either ipsi or contralateral afferents. In the generation of the “second” response supraspinal structures were involved since it never appeared in spinal animals.
It is our feeling that the activation of mechanoreceptors of vibrational type (Paccinian corpuscles) produced preferentially the “first” splanchnic reflex response.

View full abstract