The ionic current across a membrane is obtained from the extended membrane equation applicable to carrier-mediated active transport as follows:
I=-FβΔE [P_K (Cⁱ_Ke^βΔE/2-C^o_Ke^-βΔE/2) +P_Na (Cⁱ_Nae^-βΔE/2) +P_C1 (C^o_C1eβΔE/2)-φ(eβΔE/2-e^-βΔE/2)-ψe^βΔE/2]/2sinh βΔE/2, where I is current, and ΔE is voltage difference across the membrane; β=F/RT, F, R, and I have their usual thermodynamic meanings; P_jj represents the permeability coefficient of the j-th ion; φ is carrier flux, and ψ is active-transport flux. Short circuit current is given by I_SCC=Fψ.
From the phenomenological equations in irreversible thermodynamics, the cross coefficients p_ij are represented as P_j=Σⁿ>_i=1P_ij, (j=1, 2, ., n).
The current-voltage curve was observed on the abdominal skin of frogs and toads and simulated using a digital computer system. Applying the two-membrane theory, the permeability coefficients of the outer membrane of the frog skin obtained are P_Na=1.53×10^-6cm/sec, P_K=0.158×10^-6cm/sec, and P_C1=1.24×10^-6cm/sec.
Straight and cross coefficients are computed for Na⁺, K⁺, and Cl^- ions.
The relation between current carried by ions of z_j valence and that of membrane potential was represented by GOLDMAN (1943) and HODGKIN and KATZ (1949) using the following assumption concerning the constant electric field: I=-FβΔEΣⁿ_j=1P_i (C^ije^z_j^βΔE/2-C^o_j^βΔE/2) /2 sinh Z_jβΔE/2=-FβΔEΣⁿ_j=1P_jCⁱ_j+C^o_j/2-FβΔE coth Z_jβΔE/2Σⁿ_j=1Z_jP_jCⁱ_j-C^o_j/2, (1) where β=F/RT; F, R, and T have their usual thermodynamic meanings; the origin is set at the halfway point through the membrane; I and ΔE are the ionic current and the transmembrane potential, respectively; P_j represents the permeability coefficient of the j-th ion; C_jj is the concentration; and the superscripts o and i stand for the bulk phase of the outer and inner sides of the membrane, respectively.
It is obvious that the linear current-voltage relation according to Ohm's law is obtained from Eq.(1) when the ionic concentrations in the bathing solution of both sides of the membrane are equal C^o_j=Cⁱ_j (j=1, 2, ., n). In such bulk solution, e.g., in Ringer's solution, the nonlinear current-voltage curve of isolated frog skin has been described by FINKELSTEIN (1964).

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Averaged responses to photic stimuli were recorded from single cortical cells in a circumscribed small region of the nonstriate area (F_0-3 and L_2-3 in H-C coordinates) of cats. The retinas were stimulated monocularly by various stimuli, such as a diffuse light flash, an intermittent light spot, or a moving light slit, of different sizes and shapes under various conditions of dark and light adaptations. Studies were made on a total of 86 units.
1) The cortical cells had relatively large receptive fields, usually about 20°C×20°C. They were responsive to a diffuse flash, and responsiveness was influenced by background illumination.
2) The responses of 27 units to a moving slit were suppressed and those of 13 units were facilitated by background illumination.
3) Four units showed a reversal of the preferred direction.
4) Three units that had no preferred orientation in the dark developed it in the presence of background illumination.
5) The response patterns of 39 units were unaltered by background illumination.

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The characteristics of hyperpolarization occurring in the smooth muscle cell membrane of the guinea pig taenia coli during recovery after cold shock (10°C) were investigated using the doublesucrose gap method.
1. During the cold shock, the membrane resistance was initially reduced. This was followed by an increase. The membrane was depolarized throughout. The initial reduction of the membrane resistance and hyperpolarization of the membrane during rewarming showed approximately linear relationship.
2. The duration of cold shock also showed a linear relationship to the amplitude of the hyperpolarization.
3. The reduction of the membrane resistance was thought to be due to an increase of the Na conductance. The subsequent increase of the membrane resistance and depolarization were thought to be mainly due to nonselective suppression of ionic permeability and partly due to reduction of the emf.
4. In Na-free and in K-deficient solutions, the initial reduction of the membrane resistance during the cold shock and the hyperpolarization after the recovery were not observed.
5. Cl-deficient (C₆H₅SO₃) and Ca-free solutions did not suppress the generation of the hyperpolarization during the recovery process from cold shock.
6. Ouabain (10^-6g/ml) suppressed the hyperpolarization of the membrane during the recovery process.
7. The mechanisms involved in the generation of hyperpolarization during the recovery process after cold shock are discussed. The nature of the hyperpolarization is postulated to be due to activation of an electrogenic Na pump during the recovery after the cold shock.

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Effect of tetrodotoxin (TTX) on the aconitine-induced arrhythmias of the isolated cardiac tissues of the chicken embryo, the toad and the golden carp is studied by a microelectrode technique. TTX in a dose of 10^-8-10^-7g/ml antagonized the aconitine-induced rapid firing in the chicken embryo ventricle, the toad atrium and the golden carp atrium. TTX was much more potent than lidocaine in exerting an antiarrhythmic effect. The mode of action of aconitine and TTX is discussed.

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1. Effects of caffeine on tension in the dog papillary muscle were investigated using a voltage clamp with the double sucrose-gap method.
2. An S-shaped relationship between membrane potential and developed tension was obtained in Tyrode solution. An increase of the external calcium concentration produced an upward shift of the relationship and a decrease of calcium, a downward shift.
3. Caffeine (10 mM/liter) reduced the peak tension at inside positive potentials in Tyrode solution, but scarcely changed the tension at inside negative potentials.
4. An administration of caffeine retarded the relaxation phase at first, but the contraction phase was also gradually slowed.
5. The magnitude of tension elicited by an action potential after repetitive voltage clamp pulses was dependent on the magnitude of tension during prior clamp pulses in Tyrode solution, but the dependency disappeared in caffeine-treated preparations.
6. It was suggested that a tension development in the dog papillary muscle is largely regulated by the sarcoplasmic reticulum and that caffeine reduces the amounts of Ca taken up by and released from the reticulum.

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Responses of single chorda tympani fibers of rats to gustatory stimulations by monosodium glutamate (MSG) of varying concentrations with or without the presence of a fixed amount of sodium 5'-guanylate (5'-GMP) were recorded. The effect of addition of 5'-GMP to MSG differs according to the response characteristics of the unit. In units predominantly responsive to NaCl, little enhancement was observed in the response magnitude with the addition of 5'-GMP, but in units responding well to sucrose a marked enhancement occurred. In a majority of these units, not only a synergistic enhancement in the response magnitude but also a marked lowering of threshold was obtained after the addition of 5'-GMP. The relative magnitude of enhancement was greater at a lower concentration of MSG, and decreased with increasing concentration. Analysis of the concentration-response magnitude relationships suggests that the synergistic action of MSG and 5'-GMP on gustatory receptors is a mechanism known as ‘competitive and noncompetitive’ sensitization.

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1) Temperature was recorded continuously at various depths in the brain tissue of unanesthetized but moderately restrained chickens. The chickens were kept in a small round arena within a soundproof chamber and exposed to constant illumination for up to 18 days. Activity on a spring-suspended floor in the arena was recorded on print-out counters. Light intensity was varied from 0.05 to 100 lux, but was kept constant for at least 24 hr and in most experiments for several days.
2) The brain temperature and most of the activity of all chickens showed clear circadian rhythms. For each condition, the following parameters were computed: mean level of brain temperature, range of circadian oscillation, and amount of activity.
3) Level of brain temperature and amount of activity were positively correlated with light intensity. For the range of brain temperature oscillation, such a correlation was indicated by one statistical test, but the correlation was not significant with increased intensity in two other tests.
4) Range of oscillation seemed to be positively correlated with brain temperature levels at lower values, and negatively correlated at higher values of mean level.
5) The changes in brain temperature in response to changes in light intensity were rather abrupt and simultaneous in all parts of the tissue.

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Effects of oxytocin and carbachol on the membrane potential, membrane conductance, and spike potential of pregnant mouse myometrium were investigated in isotonic and hypertonic solutions.
1) In an isotonic solution low concentrations of oxytocin (10^-6-10^-5 U/ml) did not cause any change in the membrane potential or in the amplitude of the action potential, but facilitated the conduction of excitation. With these concentrations, spontaneous contractions of truncated pattern became full-size.
2) Intermediate concentrations of oxytocin (10^-4 U/ml) and carbachol (10^-5 g/ml) caused a depolarization and an acceleration of spike activity. Higher concentration of oxytocin or carbachol caused a peak depolarization to about -25 mV. During the recovery in normal solution, membranes showed oscillatory slow waves.
3) Depolarization and cessation of spike activity by 10^-3 U/ml oxytocin were maintained. The membrane tended to repolarize and resumed the spike activity in 10-20 min in the continuous presence of 10^-4 g/ml carbachol in isotonic solution.
4) In hypertonic solution the depolarization produced by these drugs was smaller, e.g., 10^-3 U/ml oxytocin or 10^-4 g/ml carbachol depolarized the membrane to -40--30 mV. When the membrane was depolarized by the drugs, membrane conductance was increased.

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Depolarizing action of 10^-3U/ml oxytocin and 10^-4g/ml carbachol on pregnant mouse myometrium in ionic solutions containing various concentrations of external Na and Ca was studied.
1) Excess Ca (10mM) caused hyperpolarization in normal and in low Na (15.5mM) solutions, and decreased membrane conductance.
2) The membrane was depolarized by about 10 mV in low Na solutions (15.5mM) and membrane conductance was decreased. Reduction of external Ca to 0.25 mM caused further depolarization and an increase membrane conductance.
3) Depolarization caused by carbachol was reduced in solutions containing low Na or excess Ca. The depolarizing action was restored by reducing external Ca to 0.25mM in low Na solutions. The peak depolarization produced by oxytocin was little affected in any of the above ionic solutions.
4) In Na-free solutions, where the membrane was depolarized to -25 mV and contracture was produced, neither oxytocin nor carbachol was effective in producing changes in membrane potential or in tension development.

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