bluuebunny/crossref_metadata_2025 huggingface dataset:
ELECTROMOTIVE CHLORIDE TRANSPORT AND GASTRIC ACID SECRETION IN THE FROG
Authors: Durbin Richard P. , Heinz Erich
Published: May 2004

The total active transport of chloride ions across the gastric mucosa can be considered as the sum of two fractions; an acidic one which is equivalent to the acid secreted, and an electromotive one which accounts for the electric energy generated by the gastric mucosa. In the present studies, the relationship between this electromotive chloride transport and acid secretion has been investigated, using specific inhibitors. The rate of electromotive chloride transport was found to be essentially unaffected by changes in the rate of acid secretion, and also by inhibition of acid secretion by thiocyanate. On the other hand, diamox, in combination with histamine, was shown to depress or abolish the gastric electromotive force and to inhibit partially the total chloride transport, while acid was secreted at an almost normal rate. This kind of inhibition is undefined as to its mechanism but seems to be more specific for the gastric chloride transport than any other inhibitor known. It is concluded that acid secretion and electromotive chloride transport involve two different mechanisms, and are not absolutely essential for each other. The present results do not support the view that carbonic anhydrase is essential for acid secretion. They rather suggest an important function of this enzyme in the mechanism of active chloride transport.
THE EFFECTIVENESS OF THE LONGITUDINAL FIELD, COUPLED WITH DEPOLARIZATION IN ACTIVATING FROG TWITCH MUSCLES
Authors: Csapo Arpad , Suzuki Taizo
Published: May 2004

Effective excitation, preceding the mechanical response in frog twitch muscles, involves two distinct events: depolarization of the excitable membrane and the flow of internal currents. To distinguish between the effects of these two potential factors in activation of the contractile machinery, experiments ought to be conducted in which one or the other is excluded. Our experiments are designed to distinguish between these effects by indirect methods.

Depolarization in a longitudinal electric field can be expected to be greatest at the ends where current leaves the muscle fibers (space constant at [K] = 16 mM/liter is >1 mm.), whereas the internal longitudinal current is known to be greatest in the middle portion. Depolarization, therefore, should affect the ends more strongly and internal current the middle portion.

Our experiments show that non-propagating frog twitch muscles shorten, during isotonic work, along their whole length and not only at their ends, when effectively stimulated in a longitudinal A.C. field. At a field strength about twice the new threshold value (at [K]o = 16 mM) shortening is distinctly greater in the middle portion of the muscle than at the ends. The muscles, although temporarily non-propagating, remain intact throughout the experiment, as demonstrated by complete recovery after repolarization.

These findings may be taken as an indication that internal currents are more directly linked to activation than is depolarization, but the latter is an essential priming step, which must precede or coincide with effective current flow.
THE EFFECT OF ENZYME INHIBITORS ON THE RESTING POTENTIAL AND ON THE ION DISTRIBUTION OF THE SARTORIUS MUSCLE OF THE FROG
Authors: Van der Kloot William G.
Published: May 2004

Isolated frog sartorii were exposed for 30 minutes to HETP—an irreversible anti-cholinesterase, and were then soaked in Ringer's at 15°C. for 16 hours. At the end of the period of soaking the mean resting potential of the muscle fibers was only 29 mv.

The decrease in the resting potential of the HETP-treated muscles was accompanied by a loss of potassium and a gain in sodium by the muscles.

The effect of anticholinesterases on sodium extrusion was studied by incubating the muscles in a Ringer's containing half of the normal amount of sodium. The muscles respond by extruding sodium against a concentration gradient into the external medium. Sodium extrusion was blocked by prior exposure of the muscle to HETP, and reversibly blocked by exposure to physostigmine. The inhibition of sodium extrusion by physostigmine was correlated with the inhibition of the intracellular cholinesterase.

Sodium extrusion was also blocked by high concentrations of 2-methyl-1,4-napthaquinone 8-sulfonic acid and by α-ketoglutarate, which are known to inhibit choline acetylase in vitro. But sodium extrusion was not affected by a third inhibitor of choline acetylase, phenobarbital.

Sodium extrusion was unaffected by KCN and partially blocked by IAA. The IAA block was eliminated by the addition of pyruvate. It is concluded that either glycolysis or oxidative metabolism can furnish the energy needed for sodium extrusion.
SODIUM EXCLUSION AND POTASSIUM RETENTION BY THE RED MARINE ALGA, PORPHYRA PERFORATA
Authors: Eppley Richard W.
Published: May 2004

Cells of the red marine alga, Porphyra perforata, accumulate potassium and exclude sodium, chloride, and calcium. Various metabolic inhibitors including dinitrophenol, anoxia, and p-chloromercuribenzoate partially abolish the cells' ability to retain potassium and exclude sodium. Iodoacetate induces potassium loss only in the dark; reduced sulfur compounds offer protection against the effects of p-chloromercuribenzoate; dinitrophenol stimulates respiration at concentrations which cause potassium loss and sodium gain.

Following exposure to anoxia potassium accumulation and sodium extrusion take place against concentration gradients. These movements are retarded by sodium cyanide, but are stimulated by light.

Sodium entry, following long exposure to 0.6 M sucrose, occurs rapidly with the concentration gradient, while potassium entry against the concentration gradient takes place slowly, and is prevented by cyanide.
THE TOPOGRAPHY OF TIP GROWTH IN A PLANT CELL
Authors: Castle Edward S.
Published: May 2004

Tips of young Phycomyces sporangiophores were dusted with starch grains, and growth photographically recorded. Rates of longitudinal displacement from the cell tip of individual markers were determined, also corresponding rates of change of cell diameter. From these the magnitude and spatial distribution of "relative elemental growth rates" along both longitudinal and circumferential axes of the cell were obtained.

Growth rates in these two directions are functions of distance from the cell apex, and have different spatial distributions. In particular, rates of growth in cell circumference are complexly patterned. Relative elemental growth rates in length and in girth are approximately equal and maximal at the cell's apex, with a value of 2.4 mm. mm.–1 hr.–1. The characteristic shape of the tip is maintained constant in the face of its changing substance and position. This shape reflects a steady state of the cell's constituent growth patterns.

At every point the growing membrane simultaneously expands in the two dimensions of its surface. The degree of polarization or directional preference of growth is measured by the ratio of longitudinal to circumferential relative elemental growth rate at any point. The ratio is not constant, but changes with position along the tip. This fact does not support the idea that membrane growth is based upon a quantal "growth event." Possible causal factors in oriented membrane growth are discussed.
WATER TRANSPORT IN INVERTEBRATE PERIPHERAL NERVE FIBERS
Authors: Nevis Arnold H.
Published: May 2004

Osmotic and diffusion permeabilities (Pf and Pd) of invertebrate nerve fibers to tritiated water were measured to determine what water flux studies could reveal about "the nerve membrane" and to directly test the possibility of active transport of water into or out of invertebrate nerve fibers. Pf/Pd ratios for lobster walking leg nerve fibers were found to be about 20 ± 7 at 14°C. Pd measurements were made for squid giant axons at 25°C. and found to yield a value of 4 x 10–4 cm.–1 sec.–1. When combined with the data of D. K. Hill for Pf, a Pf/Pd ratio of 21 ± 5 is obtained. These Pf/Pd ratios correspond to "effective pore radii" of about 16 ± 4 angstrom units, according to theories developed by Koefoed-Johnsen and Ussing and independently by Pappenheimer and his colleagues. Variations of water flux ratios with temperatures were studied and apparent activation energies calculated for both diffusion experiments and osmotic filtration experiments using the Arrhenius equation, and found to be close to 3 to 5 cal. per mole of water transferred. Cyanide (5 x 10–3 molar) and iodoacetate (1 x 10–3 molar) poisoned lobster leg nerve fibers showed no appreciable change in diffusion or osmotic filtration water effluxes. Caution in interpreting these proposed channels as simple pores was emphasized, but the possibility that such channels exist and are related to ionic flow is not incompatible with electrophysiological data.
RHYTHMICITY IN THE PROTOPLASMIC STREAMING OF A SLIME MOLD, PHYSARUM POLYCEPHALUM
Authors: Kishimoto Uichiro
Published: May 2004

The electric potential difference (1 to 15 mv.) between two loci of the slime mold connected with a strand of protoplasm changes rhythmically with the same period (60 to 180 seconds) as that of back and forth protoplasmic streaming along the strand. When atmospheric pressure at a part of the plasmodium is increased (about 10 cm. H2O), the electric potential at this part becomes positive (0 to 20 mv.) to another part with a time constant of 2 to 15 minutes. If the atmospheric pressure at a part of the plasmodium is changed (about 10 cm. H2O) periodically, the electric potential rhythm also changes with the same period as that of the applied pressure change, and the amplitude of the former grows to a new level (i.e., forced oscillation). The electric potential rhythm, in this case, is generally delayed about 90° in phase angle from the external pressure change. The period of the electric potential rhythm which coincided with that of the pressure change is maintained for a while after stopping the application of the pressure change, if the period is not much different from the native flow rhythm. Such a pressure effect is brought about by the forced transport of protoplasm and is reversible as a rule. In the statistical analysis made by Kishimoto (1958) and in the rheological treatment made in the report, the rhythmic deformation of the contractile protein networks is supposed to be the cause of the protoplasmic flow along the strand and of the electric potential rhythm. The role of such submicroscopic networks in the protoplasm in various kinds of protoplasmic movement is emphasized.
THE EFFECT OF IONS UPON THE RESPONSE OF SMOOTH MUSCLE TO COOLING
Authors: Guttman Rita , Ross Samuel M.
Published: May 2004

The slow tonic responses of the anterior byssus retractor of Mytilus edulis to rapid cooling were investigated by simultaneously recording tension and resting potential changes after soaking the muscle in banthine, a powerful neuromuscular blocking agent. The quantitative relations between the amount of cooling and the amount of associated depolarization necessary for contraction at various concentrations of potentiating potassium can be expressed in a family of curves. The plateaus of the curves for sea water and for potassium-free sea water were beneath the depolarization value necessary for contraction, so that it is clear that no amount of cooling with sea water alone or with potassium-free sea water would ever be effective. When the muscle is treated with subthreshold amounts of potassium and rapidly cooled in various concentrations of sodium ion and calcium ion, respectively, the sodium and calcium do not affect the amount of depolarization. Acetylcholine, in subthreshold amounts, has a potentiating effect, but, unlike potassium and cooling, acts through the nervous apparatus. Mytilus muscle will respond to cooling with tonic contraction whenever a critical threshold amount of depolarization is achieved. Cooling alone cannot trigger the contraction since it cannot bring about sufficient depolarization. Cooling can result in contraction, however, if used in conjunction with some other subthreshold depolarizing agent. Cooling affects the contractile mechanism by first causing membrane breakdown and depolarization.
PROLONGED ACTION POTENTIALS FROM SINGLE NODES OF RANVIER
Authors: Mueller Paul
Published: May 2004

The duration of action potentials from single nodes of Ranvier can be increased by several methods. Extraction of water from the node (e.g. by 2 to 3 M glycerin) causes increased durations up to 1000 msec. 1 to 5 min. after application of the glycerin the duration of the action potential again decreases to the normal value.

Another type of prolonged action potential can be observed in solutions which contain K or Rb ions at concentrations between 50 mM and 2 M. The nodes respond only if the resting potential is restored by anodal current.

The kinetics of these action potentials is slightly different. Their maximal durations are longer (up to 10 sec.). Like the normal action potential, they are initiated by cathodal make or anodal break. They also occur in external solutions which contain no sodium.

The same type of action potentials as in KCl is found when the node is depolarized for some time (15 to 90 sec., 100 to 200 mv.) and is then stimulated by cathodal current. These action potentials require no K or Na ions in the external medium. Their maximal duration increases with the strength and duration of the preceding depolarization. The possible origin of the action potentials in KCl and after depolarization, and their relation to the normal action potentials and the negative after-potential are discussed.
THE RATE OF UPTAKE OF CARBON MONOXIDE AND OF NITRIC OXIDE BY NORMAL HUMAN ERYTHROCYTES AND EXPERIMENTALLY PRODUCED SPHEROCYTES
Authors: Carlsen Elizabeth , Comroe Julius H.
Published: May 2004

The uptake of gases such as oxygen, carbon monoxide, or nitric oxide by the erythrocyte involves: (a) diffusion across the cellular membrane, (b) intraerythrocytic diffusion, and (c) chemical combination with hemoglobin. The aim of this investigation was to obtain data which would permit an analysis of each of these factors in limiting the rate of gas uptake.

The initial over-all rate of uptake of gases which combine chemically with hemoglobin to produce a color change can be measured by a modified version of the Hartridge-Roughton-Millikan constant flow, rapid reaction apparatus. If nitric oxide is the reactant gas, only (a) and (b) are measured since the chemical combination of this gas with hemoglobin is extremely rapid. Our studies have shown that human biconcave discoidal erythrocytes at 38 and 48°C., have the same initial rate of carbon monoxide and nitric oxide uptake as the same cells converted into spherocytes of equal volume. Similarly there was no difference between discs and cells sphered with a 30 per cent increase in volume. Shrunken erythrocytes showed a marked decrease in rate of gas uptake. This suggests that surface area and maximum linear distance for intracellular diffusion of this magnitude do not measurably retard gas uptake. In the shrunken cells, a change in the orientation and concentration of intraerythrocytic hemoglobin and/or of the membrane components may have impeded gas diffusion.
POTASSIUM-DEPENDENT SODIUM EXTRUSION BY CELLS OF PORPHYRA PERFORATA, A RED MARINE ALGA
Authors: Eppley Richard W.
Published: May 2004

Potassium-free artificial sea water causes a loss of cell potassium and a gain of cell sodium in Porphyra perforata, which is not attributable to an inhibition of respiration.

On adding KCl or RbCl to such low potassium, high sodium tissues, net accumulation of potassium or rubidium takes place, accompanied by net extrusion of sodium. Rates of potassium or rubidium accumulation and sodium extrusion are proportional to the amount of KCl or RbCl added only at low concentrations. Saturation of rates is evident at KCl or RbCl concentrations above 20–30 mM, suggesting the role of an ion carrier mechanism of transport.

Evidence for and against mutually dependent sodium extrusion and potassium or rubidium accumulation is discussed.
SOME OBSERVATIONS ON CARDIAC AUTOMATISM IN CERTAIN ANIMALS
Authors: Jensen David
Published: May 2004

Certain aspects of the acetylcholine hypothesis of cardiac automaticity have been tested in vitro with spontaneously beating cardiac tissue from rabbits, rats, dams, and hagfish. The beat of atria from rabbits and rats may be depressed or excited by acetylcholine, depending upon the state of the tissue. Proguanil and cocaine inhibition of the beat in the rat may be antagonized by acetylcholine so that reversal of the depression occurs. The action of acetylcholine on the hearts of clams was found to be strictly inhibitory. Proguanil and cocaine, in contrast to their action on mammalian atria, exert a stimulatory effect on the heart of the molluscs studied. In fact, cocaine stimulated these hearts when they were inhibited by acetylcholine.

Studies on the non-innervated hagfish heart revealed that this tissue is completely insensitive to the action of acetylcholine. Extracts prepared from beating hearts of this species will accelerate hypodynamic hearts of the hagfish as well as of the mussel. An extract of the neurogenic lobster heart was without effect on the hagfish heart. Proguanil was likewise ineffective in concentrations which produced inhibition and excitation in rat and clam hearts respectively.

It was concluded that acetylcholine does not play a role in the myogenic automatism of all species, and that another mechanism is responsible is suggested on the basis of results obtained in the hagfish hearts.
REALISTIC MODEL OF A FIXED-CHARGE MEMBRANE ACCORDING TO THE THEORY OF TEORELL, MEYER, AND SIEVERS
Authors: Mauro Alexander , Finkelstein Alan
Published: May 2004

A realistic model of a fixed-charge membrane was constructed to elucidate the principles involved in the Teorell-Meyer-Sievers theory. Polyelectrolyte solutions (polystyrene sulfonic acid or gelatin) were used in a multicompartment cell to serve as the "membrane." The ionic concentration and potential differences between the compartments served as a finite increment approximation to a continuous membrane phase. The profiles obtained for a positively and negatively charged membrane gave striking support for the theory.
EXPERIMENTAL STUDY OF OSMOSIS THROUGH A COLLODION MEMBRANE
Authors: Meschia Giacomo , Setnikar Ivo
Published: May 2004

Experiments were carried out on a collodion membrane in order to study the factors that determine direction and magnitude of net flow of water across a membrane permeable to the solvent and to some of the solutes present. The solutes used were all non-ionic. When only one solute was present and there was no difference of hydrostatic pressure across the membrane, water flowed toward the side where its vapor pressure was lower, but the rate of transfer depended upon the nature of the solute: for a given difference in osmolality across the membrane, the rate increased with the molecular volume of the solute and reached its maximum with the solute to which the membrane was impermeable. These results led to the experimental demonstration that in the presence of two or more solutes of different molecular volumes, of which one at least can diffuse through the barrier, the net transfer of water can take place against its vapor pressure gradient. Some of the physicochemical and physiological implications of the data are discussed.
IONIC TRANSFER ACROSS THE ISOLATED FROG LARGE INTESTINE
Authors: Cooperstein I. L. , Hogben C. Adrian M.
Published: May 2004

The unidirectional fluxes of sodium, chloride, and of the bicarbonate and CO2 pair were determined across the isolated large intestine of the bullfrog, Rana catesbiana. The isolated large intestine of the frog is characterized by a mean transmembrane potential of 45 mv., serosal surface positive with respect to mucosal. The unidirectional sodium flux from mucosal to serosal surface was found to be equal to the short-circuit current, thus the net flux was less than the simultaneous short-circuit current. This discrepancy between active sodium transport and short-circuit current can be attributed to the active transport of cation in the same direction as sodium and/or the active transport of anion in the opposite direction. The unidirectional fluxes of chloride and the bicarbonate and CO2 pair revealed no evidence for active transport of either anion. A quantitative study of chloride fluxes at 45 mv. revealed a flux ratio of 1.8 which is considerably less than a ratio of 6 expected for free passive diffusion. It was concluded that a considerable proportion of the isotopic transfer of chloride could be attributed to "exchange diffusion." Study of the electrical properties of the isolated frog colon reveals that it can be treated as a simple D. C. resistance over the range of -20 to +95 mv.
THE RELEASE AND STABILITY OF THE LARGE SUBUNIT OF DNA FROM T2 AND T4 BACTERIOPHAGE
Authors: Thomas Charles A.
Published: May 2004

T2 and T4 bacteriophage have been exposed to various treatments which are known to release the encapsulated DNA. The unseparated reaction products have been examined by autoradiography. The results indicate the presence of one large subunit of DNA (molecular weight 45 x 106) for each former phage particle. Some smaller subunits of molecular weight 12 x 106 have been observed.

The large subunit is sensitive to very small amounts of DNAase, and is resistant to mixed proteases and cannot be dispersed by banding in cesium chloride density gradients.

The sensitivity to fragmentation by P32 decay and the increase in this sensitivity following heat treatment are best explained by assuming that the large subunit is a duplex of polynucleotide strands over most of its length.

The presence of hypothetical non-DNA interconnections is considered.
EFFECT OF TEMPERATURE ON ELECTROLYTE METABOLISM OF ISOLATED FROG SKIN
Authors: Huf Ernst G. , Doss Norma S.
Published: May 2004

A study is presented on the effect of temperature on unidirectional active ion transport, resting electrolyte equilibrium (electrolyte composition), and oxygen consumption in isolated frog skin. The aims were twofold: first, to find out whether the rate of active transport can be changed without affecting the Na+ and K+ balance of skin itself; second, to arrive at minimal ΔNa/ΔO2 values by correlating quantitatively inhibition of active ion transport with inhibition of O2 consumption. NaCl transport was maximal at 20°C. At 28° and at temperatures below 20°, rate of NaCl transport was diminished. In many instances NaCl transport was diminished in skins which maintained their normal Na+ and K+ content. In several cases, however, neither rate of transport nor resting electrolyte equilibrium was affected; in other cases, both were.

O2 consumption decreased when lowering the temperature over the range from 28 to 10°C. From a plot of log QOO2 against 1/T an activation energy of µ 13,700 cal. was calculated, valid for the range from 10 to 20°C. It appeared that µ was smaller for temperatures above 20°C. Working between 10 and 20°, it was found that, on the average, 4 to 5 equivalents of Na+ were transported for one mole of O2 consumed in skins with undisturbed resting electrolyte equilibrium.
THE INFLUENCE OF THE MEDIUM DIELECTRIC STRENGTH UPON TRYPSIN KINETICS
Authors: Castañeda-Agulló M. , del Castillo Luz M.
Published: May 2004

The use of aqueous alkali for the titration of esterolytic activity when the esters are dissolved in alcoholic solutions, results in an error due to changes in the ionization of the buffer. This is corrected by titrating with alkali in the same solvent as the substrate.

Alcohols and other substances which change the dielectric strength of water modify the rate of hydrolysis of BAEE1 and TSAME by trypsin to an extent proportionate to their effect on the dielectric strength. The reaction rate increases with diminished dielectric strength and vice versa. At low concentrations of substance there seems to be no specific effect other than that derived of the variation in dielectric strength. At higher concentrations, the enzyme might be denatured. In addition, it is probable that specific effects of each substance might intervene. The Coulombic and thermic energies of activation were calculated for the two esters in various solvents. The plot of the logarithm of rate constant vs. reciprocal of dielectric constant yields a straight line with positive slope. This behavior is similar to that of a non-enzymatic positive ion-dipole reaction. Trypsin reacts like a positive ion. The possible influence of the dielectric strength on the regulation of the equilibria involved in the interconversion of the various forms of trypsin in solution (active, inactive, denatured) is discussed.
GROWTH DISTRIBUTION IN THE LIGHT-GROWTH RESPONSE OF PHYCOMYCES
Authors: Castle Edward S.
Published: May 2004

Elongation of sporangiophores marked with numerous starch grains was photographically recorded in the steady state and during the light-growth response when the rate is more than doubled. From these records the spatial distribution of growth within the cell's growth zone was derived.

Stimulation by a single saturating flash of light speeds growth proportionally in all parts of the growing zone, maintaining the same pattern of growth distribution as in the steady state. This finding implies that light is absorbed and acts locally throughout the length of the cell's growth zone. Cohen and Delbrück's proposal of a partial spatial separation of light reception and growth is discussed.
RECURRENT FACILITATION OF SPINAL REFLEXES
Authors: Wilson Victor J.
Published: May 2004

Antidromic volleys in muscle nerves may facilitate monosynaptic reflexes originating from neighboring motoneurons. This facilitation has been studied in spinal cats. It is at its peak with a conditioning-test interval of 20 to 30 msec., and can last 50 to 100 msec. The threshold of facilitation is about the same as that of recurrent inhibition. Both phenomena appear to be activated by stimulation of the large motor axons. The latency of facilitation seems to be longer than that of recurrent inhibition by approximately 1 msec., suggesting the presence of at least one more synaptic delay. Facilitation often follows an inhibition of variable depth and duration. Frequently, however, the facilitation is not preceded by inhibition, and therefore it cannot be a rebound effect. The pharmacological properties of facilitation resemble those of recurrent inhibition. Dihydro-beta-erythroidine1 partially blocks facilitation; the peak is decreased and occurs earlier, and the duration is shortened. Eserine increases the duration of facilitation and inhibition and sometimes enhances their magnitude. It is concluded that recurrent facilitation is mediated by the cholinergic axon collaterals, and that at least two interneurons are located between collateral and motoneuron. Possible mechanisms of facilitation are discussed.
OXYGEN CONSUMPTION OF ANIMALS AND TISSUES AS A FUNCTION OF TEMPERATURE
Authors: Fuhrman Geraldine J. , Fuhrman Frederick A.
Published: May 2004

The generally accepted view that rates of oxygen consumption of tissues and poikilotherms increase regularly with rising temperature was subjected to careful examination using brain slices and skin of rats and nine different species of aquatic and terrestrial animals. It was found that, although there are statements in the literature to the contrary, the influence of temperature is a regular one and respiration increases with rising temperature so that when rates of oxygen consumption are plotted against temperature the resulting curve is regular without dips or peaks except the maximum expected at the optimum temperature.
A LIGHT-SENSITIVE YELLOW PIGMENT FROM THE HOUSE-FLY
Authors: Bowness J. M. , Wolken J. J.
Published: May 2004

Extraction of house-fly heads with neutral phosphate buffer yielded a dark brown solution from which a number of pigments were separated, either wholly or partially, by chromatography on a column of calcium phosphate mixed with celite. One of the pigments was light-sensitive, and had a yellow color, with a spectral absorption maximum at 437 mµ in phosphate buffer at pH 6.5. Several consecutively eluted fractions from each chromatogram of the house-fly head extract showed the characteristic absorption curve of this pigment with no trace, spectroscopically, of the other pigments of the extract. The products of bleaching the pigment at pH 6.5 had an absorption curve showing plateaus at 440 to 460 mµ and 350 to 360 mµ and an inflection at about 250 mµ. Above pH 8.0 the pigment bleached in the dark giving an absorption maximum at about 380 mµ, and inflections at 290 mµ and at about 250 mµ. With 2.5 to 5 N HCl or H2SO4 an absorption maximum at 470 to 475 mµ was obtained with either the unbleached or the bleached pigment. With sulfosalicylic acid, ethanol, or heating at 100°C., a part of the pigment was precipitated, leaving a light-stable yellow supernatant.

This light-sensitive house-fly pigment cannot as yet be identified with any of the previously known insect pigments or with the photosensitive pigments of other animals, though these latter compounds exhibit some similarity in their spectroscopic properties.
ANESTHETIC AND CALCIUM ACTION IN THE VOLTAGE CLAMPED SQUID GIANT AXON
Authors: Shanes A. M. , Freygang W. H. , Grundfest H. , Amatniek E.
Published: May 2004

Changes in spike configuration and in the inward and outward currents of voltage-clamped axons agree in indicating that the increases in permeability to sodium and potassium ions during activity are depressed by procaine and cocaine and augmented by calcium. At low levels of depolarization, the effect of the multivalent ion is similar to that of the local anesthetics, in keeping with their similar effects on the threshold of excitability. The reduction of membrane conductance at rest requires a higher concentration of the drugs than that needed to affect the increase in permeability with activity.
CALCIUM INFLUX IN SKELETAL MUSCLE AT REST, DURING ACTIVITY, AND DURING POTASSIUM CONTRACTURE
Authors: Bianchi C. Paul , Shanes A. M.
Published: May 2004

Calcium influx in the sartorius muscle of the frog (Rana pipiens) has been estimated from the rate of entry of Ca45. In the unstimulated preparation it is about equal to what has been reported for squid giant axons, but that per impulse is at least 30 times greater than in nerve fibers. The enhanced twitch when NO-2 replaces Cl- in Ringer's is associated with at least a 60 per cent increase in influx during activity, whereas this anion substitution does not affect the passive influx significantly. Calcium entry during potassium contracture is even more markedly augmented than during electrical stimulation, but only at the beginning of the contracture; thus, when a brief Ca45 exposure precedes excess K+ application, C45 uptake is increased three- to fivefold over the controls not subjected to K+, whereas when C45 and K+ are added together, no measurable increase in Ca45 uptake occurs. These findings are in keeping with the brevity of potassium contracture in "fast (twitch)" fibers such as in sartorius muscle.
THE PENETRATION OF SOME CATIONS INTO MUSCLE
Authors: Mullins L. J.
Published: May 2004

The influx of Na+, K+, Rb+, and Cs+ into frog sartorius muscle has been followed. The results show that a maximum rate is found for K+, while Na+ and Cs+ penetrate much more slowly. Similar measurements with Ca++, Ba++, and Ra++ show that Ba++ penetrates at a rate somewhat greater than that of either Ca++ or Ra++. All these divalent cations, however, penetrate at rates much slower than do the alkali cations. The results obtained are discussed with reference to a model that has been developed to explain the different penetration rates for the alkali cations.
THE CHEMISTRY OF INSECT HEMOLYMPH
Authors: Wyatt G. R. , Meyer W. L.
Published: May 2004

Free glycerol has been identified as a major solute in plasma of pupae of the silk moth, Hyalophora cecropia. Glycerol is not found in the blood of larvae; it appears about the time of pupation, and then gradually accumulates during diapause to reach after 6 months a level of about 0.3 M. When diapause is broken and the adult develops, glycerol rapidly disappears. In diapausing pupae of the related species, Telea polyphemus, about 0.05 M glycerol was found; in 3 other saturniid species, there was little or none. It is suggested that glycerol may be a product of a modified glycolytic pathway.
AN ANALYSIS OF CONDUCTANCE CHANGES IN SQUID AXON
Authors: Mullins L. J.
Published: May 2004

The membrane of the squid axon is considered on the basis of a pore model in which the distribution of the pore sizes strongly favors K+ transfer when there is no potential. Electrical asymmetry causes non-penetrating ions on the membrane capacitor to exert a mechanical force on both membrane surfaces and this force results in a deformation of the membrane pore system such that it assumes a distribution of sizes favoring the ions exerting mechanical force. The ions involved appear to be Ca++ on the outside of the membrane and isethionate-, (i-) on the inside; as Ca++ is equivalent in size to Na+, the charged membrane is potentially able to transfer Na+, when the ions deforming the membrane pore distribution are removed. A depolarization of the membrane leads to an opening of pores that will allow Na+ penetration and a release of the membrane from deformation. The pores revert to the zero-potential pore size distribution hence the Na permeability change is a transient. Calculation shows that the potassium conductance vs. displacement of membrane potential curve for the squid axon and the "inactivation" function, h, can be obtained directly from the assumed membrane distortion without the introduction of arbitrary parameters. The sodium conductance, because it is a transient, requires assumptions about the time constants with which ions unblock pores at the outside and the inside of the membrane.
SYNAPTIC COMPONENTS OF CEREBELLAR ELECTROCORTICAL ACTIVITY EVOKED BY VARIOUS AFFERENT PATHWAYS
Authors: Purpura D. P. , Girado M. , Grundfest H.
Published: May 2004

Electrical responses evoked in different regions of the cerebellar cortex of cat by stimulating various cerebello-petal pathways have been analyzed for their component postsynaptic potentials (p.s.p.'s). The principal analytical tools of the present work were pharmacological agents; the selective inactivator of depolarizing (excitatory) axodendritic synapses, γ-aminobutyric acid (GABA, or C4); the homologous C6 and C8 ω-amino acids, which inactivate selectively the hyperpolarizing (inhibitory) axodendritic synapses; and the general inactivator of inhibitory synapses, strychnine. Some experiments employed the analytical possibilities of activity cycles.

The potentials evoked in one cerebellar region by different exciting pathways may differ markedly in their responses to drugs or may show different types of activity cycle. Also, the potentials evoked in various cortical regions by one cerebello-petal pathway are acted upon differently by the testing drugs. These differences are believed to be due to involvement of different proportions of excitatory and inhibitory, axosomatic and axodendritic p.s.p.'s. The analyses of a number of different responses confirm an earlier conclusion, that the cerebellar cortex is relatively lacking in inhibitory axodendritic p.s.p.'s in comparison with the cerebral cortex. Only the cortex of the paramedian lobule appears to be endowed with a considerable proportion of inhibitory p.s.p.'s, a finding which correlates with other data.
THE DISTRIBUTION AND KINETICS OF RELEASE OF RADIOCALCIUM IN TENDON AND SKELETAL MUSCLE
Authors: Shanes A. M. , Bianchi C. P.
Published: May 2004

The distribution of Ca45 in frog (Rana pipiens) sartorius muscle, after 4 hours' exposure to Ringer's solution containing radiocalcium, has been analyzed by observing the kinetics of escape of the radioisotope into a non-radioactive Ringer's solution with calcium present or absent and by assuming that the tendon of Achilles is a satisfactory model of the extent of the uptake and release of Ca45 by the interstitial connective tissue (c.t.). In a Ringer's solution containing 1 mM/liter calcium, the exchangeable calcium distribution in micromoles per gram wet weight is as follows: (a) Aqueous phase of c.t. space: 0.16; (b) bound to c.t.: 0.16; (c) bound to surface of fibers: 0.13, of which 0.03 is displaced only by self-exchange, whereas the rest, as in c.t., can be displaced by other ions; and (d) in myoplasm: 0.33. The kinetics of Ca45 exit suggests that in infinite time of exposure to Ca45 the myoplasmic component would rise to 0.85. In the muscles, the half-time of the quickly emerging Ca45 averages about 3 minutes, whereas the time constant of the slowly released component is about 500 minutes. In the tendons the percentage rate of escape falls exponentially, the half-time of emergence being about 10 minutes.
STUDIES ON THE SODIUM AND POTASSIUM TRANSPORT IN RABBIT POLYMORPHONUCLEAR LEUKOCYTES
Authors: Elsbach Peter , Schwartz Irving L.
Published: May 2004

Rabbit polymorphonuclear leukocytes obtained from peritoneal exudates, incubated at 37°C. following exposure to 4°C., actively reaccumulate potassium while little or no net extrusion of sodium takes place. Preventing the utilization of oxidative metabolism with potassium cyanide, 2,4-dinitrophenol, or a nitrogen atmosphere does not inhibit the recovery process. Inhibitors blocking anaerobic glycolysis (sodium iodoacetate and sodium fluoride in low concentrations) completely abolish the capacity to reaccumulate potassium and cause a further dissipation of the sodium and potassium gradients. Water movements have been shown to be secondary to cation shifts. It is postulated that separate transport mechanisms exist for sodium and potassium and that the process of potassium reaccumulation relies on anaerobic glycolysis as a source of energy.
PARAMETERS OF GASEOUS ION EFFECTS ON THE MAMMALIAN TRACHEA
Authors: Krueger Albert P. , Smith Richard F.
Published: May 2004

A. Duration of Effects

Groups of mice exposed to high densities of unipolar light air ions for 72 hours exhibited persistent alterations in the functional efficiency of their tracheas. These effects lasted at least 4 weeks, and in the case of animals treated with (+) ions included diminished ciliary activity, pale and contracted tracheal mucosa, and enhanced vulnerability to trauma.

Following treatment with (-) ions, animals displayed increased ciliary activity with no other detectable changes. It required at least 60 minutes of exposure to ions to induce such "permanent" functional changes.

B. Minimal Effective Ion Densities

The minimal ion densities producing changes in ciliary activity within an arbitrary period of 30 minutes were determined with extirpated tracheal strips from rabbits and guinea pigs. The threshold value for (-) ions was approximately 2.5 x 103 ions/cm.2/sec. and that for (+) ions was in the range between 1 x 104 and 2.5 x 105 ions/cm.2.

The minimal ion densities producing changes in ciliary activity within an arbitrary period of 30 minutes were determined with extirpated tracheal strips from rabbits and guinea pigs. The threshold value for (-) ions was approximately 2.5 x 103 ions/cm.2/sec. and that for (+) ions was in the range between 1 x 104 and 2.5 x 105 ions/cm.2.

The evidence indicates that ion-induced functional changes in the ciliated epithelium of the pulmonary tree are the results of direct contact of ions with surface cells and do not involve participation of the central nervous system or circulation. So far as ciliary activity is concerned, the number of ions required to produce a change in rate is very small.
RUBIDIUM AND CESIUM FLUXES IN MUSCLE AS RELATED TO THE MEMBRANE POTENTIAL
Authors: Sjodin Raymond A.
Published: May 2004

The reduction of membrane potential in frog sartorius muscle produced by rubidium and cesium ions has been studied over a wide concentration range and compared with depolarization occasioned by potassium ions. The constant field theory of passive flux has been used to predict the potential changes observed. The potential data suggest certain permeability coefficient ratios and these are compared with ratios obtained from flux data using radioactive tracers. The agreement of the flux with the potential data is good if account is taken of the inhibition of potassium flux which occurs in the presence of rubidium and cesium ions. A high temperature dependence has been observed for cesium influx (Q10 = 2.5) which is correlated with the observation that cesium ions depolarize very little at low temperatures. The observations suggest that cesium ions behave more like sodium ions at low temperatures and more like potassium ions at room temperature with respect to their effect on the muscle cell resting potential. The constant field theory of passive ion flux appears to be in general agreement with the experimental results observed if account is taken of the dependence of permeability coefficients on the concentrations of ions used and of possible interactions between the permeabilities of ions.
PROTOPLASMIC STREAMING OF AN INTERNODAL CELL OF NITELLA FLEXILIS
Authors: Kishimoto Uichiro , Akabori Hiromichi
Published: May 2004

The sudden cessation or sudden decrease in velocity of the protoplasmic streaming of Nitella flexilis is observed whenever an action potential is elicited. The action potential can be generated by an electric stimulus after its refractory period, whether the flow is at a complete standstill or on the way to recovery. The membrane potential is generally decreased more or less when the rate of flow is decreased on application of salts or other agents. There is, however, no parallelism between these two. The membrane potential decreases proportionally with applied voltage of subthreshold intensity, while the rate of flow does not change appreciably. Only on application of a superthreshold voltage does the flow stop suddenly. In one case the rate of flow decreased to half without appreciable decrease in membrane potential. In another case it continued flowing at about one-half rate, although the membrane potential was almost zero. The Q10 of the rate of flow is about 2, while it is 1.1 to 1.5 for the membrane potential.

The sudden cessation of the protoplasmic streaming is supposed to be caused by the temporary formation of certain interlinkages among contractile protein networks in the endoplasm during excitation at the cathodal half of Nitella.
FUNCTIONAL ORGANIZATION IN THE TERMINAL SEGMENTS OF THE SPINAL CORD WITH A CONSIDERATION OF CENTRAL EXCITATORY AND INHIBITORY LATENCIES IN MONOSYNAPTIC REFLEX SYSTEMS
Authors: Lloyd David P. C. , Wilson Victor J.
Published: May 2004

Prominent monosynaptic and disynaptic reflex discharges characterize ipsilateral reflex transmission in the third sacral segment. Convergence upon the motoneurons from the two sides of the body is inhibitory, that through disynaptic paths excitatory. The relative latencies of excitation and inhibition of reflex responses, of excitatory and inhibitory synaptic potentials, and of various aspects of impulse discharge in motoneurons are considered. It is concluded: (1) that a direct (i.e. monosynaptic) action of primary afferent collaterals upon motoneurons is responsible for inhibition of monosynaptic reflex discharge of antagonist motoneurons within a myotatic unit; (2) that the inhibitory postsynaptic potential as described is not the primary agency for monosynaptic reflex inhibition of monosynaptic reflex discharge; (3) that, however, a common causal agent may be responsible for inhibition of reflex discharge and for generation of an inhibitory postsynaptic potential; and (4) that the inhibitory post-synaptic potential may be linked with, or be the agent for, inhibition of soma response.
THE POTENTIAL OF WATER IN MAMMALIAN TISSUES
Authors: Maffly Roy H. , Leaf Alexander
Published: May 2004

Melting point depression was used as an index of the water potential of rat tissues and serum. Organs removed from anesthetized rats were immediately frozen in liquid nitrogen and ground with mortar and pestle. Aliquots of the resulting frozen powder were suspended in chilled liquid silicone. While the suspension was vigorously stirred and warmed at a constant rate, the temperature of the melting mixture was measured.

The melting curves of rat muscle, liver, heart, and brain were not significantly different from those of rat serum. The melting curve depression of whole kidney was greater than that of serum; this was demonstrated to be due to hypertonicity of the renal medullary area alone. It was demonstrated that autolysis will rapidly increase the depression of the melting curve of tissue. It is concluded that within the limits of the method used the melting point depression, and hence the water potential, of intracellular and extracellular fluids is the same.
SODIUM AND POTASSIUM BINDING BY RAT LIVER CELL MICROSOMES
Authors: Sanui Hisashi , Pace Nello
Published: May 2004

The effects of ion concentration, pH, and presence of competing ions on the sodium and potassium binding properties of rat liver cell microsomes were studied. Typical adsorption isotherms were obtained in the concentration dependence studies, with saturation being reached when 1.2 to 1.4 m.eq. cations were retained per gm. of microsome Kjeldahl nitrogen. The retention was shown to be due to a binding to specific sites rather than to a trapping of the cations. The binding showed a sharp pH dependence in the range 6.0 to 7.5. The presence of one cation depressed the binding of the other, indicating that Na+ and K+ as well as H+ ions compete for the same sites. Potassium was bound slightly more strongly than sodium, while hydrogen was bound about 105 times more strongly than either. Calculations show that the binding follows the simple mass law.

Similarities between adsorption by microsomes and adsorption by synthetic cation exchange resins are discussed and compared to some of the characteristics of electrolyte behavior in living systems. A possible ion exchange elution, active cation transport mechanism is suggested, involving the preferential elution of Na+ out of the cell by H+ ions produced by metabolism.
Effect of the Medium Dielectric Strength on the Activity of Alpha Chymotrypsin
Authors: Castañeda-Agulló M. , del Castillo Luz M.
Published: May 2004

The rates of hydrolysis of TrEE, TEE, and ATEE1 by α-chymotrypsin were determined in media of variable dielectric strength. Many substances which modify the dielectric constant of the medium, exert additional specific effects on the reaction rate, noticeable at more or less elevated concentrations. Notwithstanding, it is possible to differentiate the dielectric and specific effects by comparing the rates in solvents of distinct nature at relatively low concentrations. Thus, the effect of varying the dielectric strength could be studied within wider ranges (ΔD = 20 with TrEE and ca. 28 with ATEE) than in the previous study of trypsin (ΔD = 12). The dielectric effect on α-chymotrypsin is the opposite of that observed with trypsin. In both cases there is a linear relationship between the logarithm of the rate of hydrolysis and the reciprocal of the dielectric constant. The slope is negative with α-chymotrypsin and positive with trypsin. According to expressions relating the dielectric constant to the rate in non-enzymatic reactions, the behavior of α-chymotrypsin is like that of a negative ion, while trypsin behaves as a positive ion. The enzyme activity appears to depend upon the arrangement of charges in the enzyme and substrate molecules, rather than on the presence of certain atomic groupings in the substrate.