bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of Oxytocics on the "Ca-Deficient" Uterus
Authors: Coutinho Elsimar M. , Csapo Arpad
Published: May 2004

If the excised, parturient rabbit uterus is repeatedly treated with a Krebs solution free from Ca, its tension in a tetanus drops gradually, and in 15 to 30 minutes becomes zero. We call such a uterus "Ca-deficient." The uterus in this condition has a high threshold, it is non-propagating, "inexcitable," fails to respond to oxytocics in a characteristic fashion, but retains maximum contractility. As Ca is gradually restored to the Krebs, these lost qualities return in a graded fashion and tension of the tetanized uterus becomes a log function of the [Ca]. If the [Ca] is kept low, i.e. 1/10 to 1/20 of the normal, tetanic tension is small but steady, and the preparation offers a full scale of tension increment for the measurement of oxytocic potency. Keeping the stimulus and the [Ca] constant, excitability (measured by tension increment) is a log function of the drug concentration. The recovery of excitability by restoring Ca to the Ca-deficient uterus is strongly temperature-dependent. The Ca-deficient uterus is a useful preparation for the study of the mechanism of regulation. When its excitability is partially recovered by Ca, the electrically stimulated uterus becomes an excellent tool for the quantitative measurement of oxytocic potency.
Potassium Accumulation and Sodium Efflux by Porphyra perforata Tissues in Lithium and Magnesium Sea Water
Authors: Eppley Richard W.
Published: May 2004

Cells of Porphyra perforata, a red marine alga, accumulate K in the absence of concomitant Na or Li extrusion while immersed in Li- or Mg-sea waters lacking Na. This suggests that the coupling observed between K and Na transport is facultative. No evidence is obtained for net extrusion of Li.

Na efflux, with the concentration gradient, is facilitated by K and is proportional to the cellular Na content. Either Na efflux does not involve an ion carrier or the number of Na sites is large.

Because K accumulation has been observed in the absence of Na extrusion, but not vice versa, it seems that K uptake is the primary secretory event, with Na extrusion a secondary process dependent upon K accumulation.
Muscle: A Three Phase System
Authors: Frater R. , Simon Shirley E. , Shaw F. H.
Published: May 2004

The partition of sulfate, Ca++, and Mg++ across the membrane of the sartorius muscle has been studied, and the effect of various concentrations of these ions in the Ringer solution on the cellular level of Na+, K+, and Cl- has been determined.

The level of the three divalent ions in toad plasma and muscle in vivo has been assayed. Muscle was found to contain an almost undetectable amount of inorganic sulfate.

Increases in the external level of these ions brought about increases in intracellular content, calculated from the found extracellular space as determined with radioiodinated serum albumin or inulin. Less of the cell water is available to sulfate than to Cl-, and the Mg++ space is less than the Na+ space. An amount of muscle water similar to that found for Li+ and I- appears to be available to these divalent ions. Sulfate efflux from the cell was extremely rapid, and it was not found possible to differentiate kinetically between intra- and extracellular material.

These results are consistent with the theory of a three phase system, assuming the muscle to consist of an extracellular phase and two intracellular phases. Mg++ and Ca++ are adsorbed onto the ordered phase, and increments in cellular content found on raising the external level are assumed to occur in the free intracellular phase.
An All-or-None Response in the Release of Potassium by Yeast Cells Treated with Methylene Blue and Other Basic Redox Dyes
Authors: Passow Hermann , Rothstein Aser , Loewenstein Barbara
Published: May 2004

Basic redox dyes, such as methylene blue, induce a loss of K+ from yeast cells. The maximal loss, rather than the rate of loss, is related to the dye concentration, the response following a normal distribution on a plot of log-dose, versus percentage loss of K+. This fact taken together with the observed correlation between K+ loss and frequency of staining (as measured by microscopic observation), indicates that the response is all-or-none for individual cells. The response is produced by all the basic redox dyes tested (9), but by none of the acidic dyes (4). However, only the oxidized form of the dye is effective. Cations protect the cells from the basic dyes in a competitive manner, the bivalent cations (especially UO2++) being more effective than monovalent cations. It is suggested that the action of the dyes involves two steps, the first a binding to ribonucleic acid in the cell membrane (with competition from cations) and the second, an oxidation of neighboring sulfhydryl groups to the disulfide form. At a threshold level, unique for each cell, a generalized membrane breakdown occurs, resulting in the release of potassium and of other cytoplasmic constituents.
The Creatine Phosphoryltransfer Reaction in Iodoacetate-Poisoned Muscle
Authors: Carlson Francis D. , Siger Alvin
Published: May 2004

The iodoacetate-nitrogen-poisoned muscle offers the possibility of studying the stoichiometry of the single muscle twitch since metabolic resynthesis by glycolysis and oxidative phosphorylation are blocked, and there remains as an energy source only the creatine phosphoryltransfer system, creatine phosphate reacting with adenosinediphosphate to give the triphosphate and creatine. It is shown, preparatory to a determination of the amount of phosphocreatine split in a single twitch, that iodoacetate does not inhibit creatine phosphoryltransferase at concentrations which block glycolysis. An analysis is developed which assumes that the transferase maintains the creatine phosphoryl transfer reaction in equilibrium following contraction, and further that the creatine phosporyltransfer reaction and the myokinase reaction are isolated in muscle. On the basis of this analysis and the data obtained, an estimate of the equilibrium constant of the creatine phosphoryl reaction in muscle is obtained which agrees with values determined in vitro. Using the estimated equilibrium constant, and the concentrations of creatine, creatine phosphate, and adenosinetriphosphate found, a value for the concentration of free adenosinediphosphate is obtained which is considerably less than that found by direct chemical analysis.
Radiocalcium Release by Stimulated and Potassium-Treated Sartorius Muscles of the Frog
Authors: Shanes A. M. , Bianchi C. P.
Published: May 2004

Stimulation of frog (Rana pipiens) sartorius muscle accelerates release of Ca45, but only during the period of stimulation. No appreciable difference is obtained in the calcium released per impulse whether stimulation is at a rate of 20/sec. or 0.5/sec. However, prior stimulation may appreciably increase the loss per impulse. In unfatigued muscles, the minimum amount of calcium liberated during an isotonic twitch is estimated to be about that previously calculated to enter, viz. 0.2 µµmole/cm2.

The time course of radiocalcium release during potassium depolarization depends on the nature of the contracture. When contracture is isometric, the rate of escape is doubled and declines only slowly; if isotonic, the rate is quadrupled but declines in a few minutes to a level maintained at about double that before potassium. The minimal calcium release during the first 10 minutes of potassium treatment is estimated to be about the same in both cases and about one-half to one-third the uptake. This, and especially the close equality of calcium entry and exit during electrical stimulation, are pointed out as not necessarily inconsistent with a transitory net entry of calcium, comparable to the influx, into restricted regions of the individual fibers.
Recurrent Conditioning in the Cat Spinal Cord
Authors: Wilson Victor J. , Talbot William H.
Published: May 2004

The action of cumulative doses of meprobamate on antidromic conditioning has been studied in spinal cats. Recurrent facilitation is greatly reduced or completely abolished by total doses ranging from 210 to 400 mg./kg. The depth of recurrent inhibition is not affected in a consistent manner by meprobamate, but the duration of inhibition is markedly increased in all experiments. This differential action of meprobamate on facilitation and inhibition can be utilized to study conditioning effects consisting of combined inhibition and facilitation. If conditioning starts with an inhibitory phase, variable in duration, followed by facilitation, meprobamate depresses the facilitation and reveals an extended inhibitory curve. Facilitation, however, is not always accompanied by inhibition, since in some cases facilitation is depressed and no inhibition is uncovered. The results of these experiments are discussed in relation to the various types of conditioning that have been produced by antidromic stimulation.
Studies on the Distribution of Factor I and Acetylcholine in Crustacean Peripheral Nerve
Authors: Florey Ernst , Biederman M. A.
Published: May 2004

Extracts of whole nerve (chelipeds of Cancer magister) cause inhibition of impulse generation of the crayfish stretch receptor preparation, similar to that produced by gamma-aminobutyric acid (GABA). This is not found with extracts containing only sensory or sensory and motor fibers. Extracts of inhibitory fibers inhibit the stretch receptor discharge—indicating an inhibitory action equivalent to that of up to 30,000 micrograms of GABA per gm. wet weight of inhibitor fiber. This high value is taken as an indication that the inhibitory substance in crab inhibitory fibers is not identical with gamma-aminobutyric acid.

Whole nerves were found to contain 1.7 to 6.7 µg. acetylcholine per gm. nerve tissue (clam ventricle and frog rectus abdominis muscle). No acetylcholine could be detected in extracts of motor and inhibitory fibers. The acetylcholine content of sensory fibers can account for the acetylcholine activity of whole nerve extract.

It is concluded that the factor I of crustacean nerve is an exclusive property of the inhibitory fibers. The results support the assumption that factor I is the transmitter substance of inhibitory neurons in these animals.

The absence of acetylcholine in motor fibers indicates that this substance does not function as a transmitter of motor impulses in Crustacea, and explains the previously observed failure of the substance to elicit motor responses in these animals. The function of acetylcholine in sensory fibers is not yet clarified.
The Biological Mechanisms of Air Ion Action
Authors: Krueger Albert P. , Smith Richard F.
Published: May 2004

Intravenous administration of 5-hydroxytryptamine to rabbits and guinea pigs is shown to bring about changes very similar to those produced by (+) air ions, including (1) decreased ciliary rate, (2) contraction of the posterior tracheal wall, (3) exaggerated response of the tracheal mucosa to trauma, (4) marked vasoconstriction in the tracheal wall, and (5) increased respiratory rate. These effects are reversed by (-) air ions. Iproniazid, which raises 5-hydroxytryptamine levels in the animal by blocking monamine oxidase, produces similar but non-reversible effects. Reserpine, which depletes 5-hydroxytryptamine in the animal, causes changes that resemble those produced by (-) air ions, including (1) increased ciliary rate, (2) relaxed posterior sulcus, (3) hyperemia of the tracheal mucosa, (4) lowered respiratory rate, and (5) increased volume and rate of mucus flow.

On the basis of these facts, the hypothesis is advanced that (+) air ion effects are mediated by the release of free 5-hydroxytryptamine, while (-) air ion effects depend on the ability of (-) ions to accelerate the enzymatic oxidation of 5-hydroxytryptamine.
Photoreactivation of Transforming DNA by an Enzyme from Bakers' Yeast
Authors: Rupert Claud S.
Published: May 2004

Ultraviolet-inactivated Hemophilus influenzae transforming DNA recovers its activity when mixed with cell-free extracts of bakers' yeast and exposed to visible light. The active agent in the extract is not used up in the reaction, and purification has not separated it into more than one non-dialyzable component. It differs from the agent in Escherichia coli extract, which produces very similar photoreactivation, but which can be resolved into non-dialyzable and dialyzable components, the latter being used up during illumination.

The yeast agent can be salted out of solution and recovered quantitatively; it is inactivated by crystalline trypsin and chymotrypsin and by brief heating at 60°C.—all facts suggesting that it is an enzyme for which ultraviolet lesions in the DNA serve as substrate. The kinetics of recovery are also consistent with such an assumption.

This enzyme is unusual both because it is involved in a light-dependent reaction and because it has a non-destructive action on DNA outside an intact cell.
The Binding of Mercury by the Yeast Cell in Relation to Changes in Permeability
Authors: Passow Hermann , Rothstein Aser
Published: May 2004

Yeast cells exposed to mercuric chloride suffer irreversible damage to the membrane, resulting in a loss of potassium and cellular anions to the medium. The maximal loss of K+, but not the time course of K+ loss is related to the mercury concentration, the relationship following a normal curve on a graph of log-concentration versus effect. It is concluded that the response is all or none for individual cells, and that with increasing concentrations of metal, the threshold is exceeded in an increasing proportion of the cells. Parallel studies of the binding of mercury by the cells indicate two distinct phases, only one of which is associated with the physiological response. The binding process is relatively slow but reaches an equilibrium state. Desorption is markedly dependent on temperature. No simple stoichiometric relationship exists between the binding of mercury and the physiological response (K+ loss).
Integrative Synaptic Mechanisms in the Caudal Ganglion of the Crayfish
Authors: Preston James B. , Kennedy Donald
Published: May 2004

A study of activity recorded with intracellular micropipettes was undertaken in the caudal abdominal ganglion of the crayfish in order to gain information about central fiber to fiber synaptic mechanisms. This synaptic system has well developed integrative properties. Excitatory post-synaptic potentials can be graded, and synaptic potentials from different inputs can sum to initiate spike discharge. In most impaled units, the spike discharge fails to destroy the synaptic potential, thereby allowing sustained depolarization and multiple spike discharge following single pulse stimulation to an afferent input. Some units had characteristics which suggest a graded threshold for spike generation along the post-synaptic fiber membrane. Other impaled units responded to afferent stimulation with spike discharges of two distinct amplitudes. The smaller or "abortive" spikes in such units may represent non-invading activity in branches of the post-synaptic axon. On a few occasions one afferent input was shown to inhibit the spike discharge initiated by another presynaptic input.
Efflux of Red Cell Water into Buffered Hypertonic Solutions
Authors: Olmstead Edwin G.
Published: May 2004

Buffered NaCl solutions hypertonic to rabbit serum were prepared and freezing point depressions of each determined after dilution with measured amounts of water. Freezing point depression of these dilutions was a linear function of the amount of water added. One ml. of rabbit red cells was added to each 4 ml. of the hypertonic solutions and after incubation at 38°C. for 30 minutes the mixture was centrifuged and a freezing point depression determined on the supernatant fluid. The amount of water added to the hypertonic solutions by the red cells was calcuated from this freezing point depression. For each decrease in the freezing point of -0.093°C. of the surrounding solution red cells gave up approximately 5 ml. of water per 100 ml. of red cells in the range of -0.560 to -0.930°C. Beyond -0.930°C. the amount of water given up by 100 ml. of red cells fits best a parabolic equation. The maximum of this equation occurred at a freezing point of the hypertonic solution of -2.001°C. at which time the maximum amount of water leaving the red cells would be 39.9 ml. per 100 ml. of red cells. The data suggest that only about 43 per cent of the red cell water is available for exchange into solutions of increasing tonicity.
The Nature and Significance of the Bohr Effect in Mammalian Hemoglobins
Authors: Riggs Austen
Published: May 2004

The oxygenation of hemoglobins is accompanied by the dissociation of protons. The number of protons discharged is inversely related to the size of the mammal from which the hemoglobin comes. The number of mercuric ions which are immediately bound by hemoglobins is approximately equal to the number of protons dissociated during oxygenation. Pretreatment of human hemoglobin by N-ethylmaleimide, which appears to bind only sulfhydryl groups prevents the binding of any mercuric ions under conditions when mercuric ions would otherwise be bound. These facts suggest that those mammals with higher metabolic rates will generally possess hemoglobins with a larger number of appropriately placed cysteine residues.
The Movement of Thallium Ions in Muscle
Authors: Mullins L. J. , Moore R. D.
Published: May 2004

Measurements have been made of the fluxes of thallous ions (Tl+) across the membrane of frog sartorius muscle fibers. These show that at an external concentration of 74 µM the influx is about 270 x 10-15 moles/cm.2 sec., while the efflux from a muscle with an internal concentration equal to the above is 5 x 10-15 moles/cm.2 sec. The efflux is increased of the order of 300-fold during a muscle twitch, and Tl+ reach a steady-state distribution between fiber water and Ringer solution that is very close to the corresponding ratio for K+. High concentrations of Tl+ depolarize the membrane about 58 mv. for a tenfold increase in external concentration. The results obtained are consistent with the view that the muscle fiber membrane cannot distinguish between the toxic heavy metal Tl+ and K+, provided that the concentrations of the former ion are kept low. High concentrations of Tl+, if allowed to act for an appreciable period of time, lead to irreversible damage to muscle.
The Rate of Proflavin Passage into Single Living Cells with Application to Permeability Studies
Authors: Robbins Elliott
Published: May 2004

A technique for the measurement of the uptake rate of proflavin by the single cell in tissue culture has been developed, and the kinetics of the dye transport are discussed in terms of its physicochemical properties. Some applications of the technique to the study of permeability are given.
The Conjugated Plasma Proteins of the American Cockroach
Authors: Siakotos A. N.
Published: May 2004

Evidence has been presented for the possible transport function of conjugated roach plasma proteins during molting. Extensive changes in these proteins are evident during the premolt stage. The remainder of the instar appears to be devoted to a gradual return to the intermolt stage. This recovery process is characterized principally by a transformation of less mobile lipoproteins to lipoproteins of higher electrophoretic mobilities and may be indicative of a lipoprotein-lipase reaction in insects. This transformation also appears to give rise to a second sex-specific lipoprotein. Significant changes in the glycoproteins at the premolt and ecdysial stages may indicate transport of carbohydrate for storage or utilization. A total of six fractions has been shown to occur in roach plasma in the period from one molt to the next.

The process of clotting appeared to be concerned primarily with the blood lipoproteins. These protein fractions reacted to form two new lipoproteins, one of which was the relatively insoluble coagulum network. The second major protein fraction appearing as a result of the coagulation process also was a lipoprotein which contained a lower concentration of carbohydrate than the clot. A possible method of assaying or screening new anticoagulants for insect blood is proposed.
The Effect of Polarized Light on the Growth of a Transparent Cell
Authors: Jaffe L. F.
Published: May 2004

It is shown that light lost by reflection before entering a clear and homogeneous sphere or infinite cylinder is precisely compensated by light retained within these bodies by internal reflection; compensation means that the total rate of light absorption by infinitely dilute photoreceptors as integrated through the whole of these bodies or even through any concentric or coaxial shell making them up is independent of surface reflection. In the Phycomyces sporangiophore this theorem precludes a reflection explanation of R, the polarization dependence of the light growth response.

An alternative explanation based upon anisotropic absorption by the receptors is explored and found tenable. Formulae are derived for R in any transparent cylindrical cell as a function of the constants of anisotropic absorption by the photoreceptors taken as a group (CH' and CL'), of the radial position of the receptors, and of the refractive indices of the cell (n) and of the medium (N). It is inferred that the photoreceptors in the Phycomyces sporangiophore are most absorbent for light vibrating in the direction of a hoop around a barrel. Orientation of the receptors by linkage to the cell wall is then shown to be a plausible explanation of the inferred anisotropy. On the basis of anisotropic reception, it is predicted that R should be constant for any N > n, and it is shown how CH', C,L' and the radial position of the receptors may all be obtained from a careful determination of R as a function of N.
An Adenosinetriphosphate-Activated Hemolytic System
Authors: Borek Blanche Ann , Zaffuto Stephen F. , Bovarnick Max
Published: May 2004

Lysis of human red cells in vitro by an enzyme obtained from rabbit red cell hemolysates and the inhibition of this lytic activity by human stroma have been shown to require Mg++ and ATP, and ATP utilization has been demonstrated in both reactions. We find that sodium or potassium ions are also required for the lytic phenomenon and that they enhance the inhibition. The rate of hemolysis is not affected by the internal concentrations of these ions but depends only on the external concentration. The rate of influx and efflux of Na22Cl and K42Cl in surviving red cells is greatly enhanced both during and after treatment with rabbit hemolytic factor whereas the entry of C24-sucrose, a small foreign molecule, is mediated only in the presence of hemolytic factor. Glycolysis neither protects against lysis nor enhances the activity of this system, and cardiac glycosides which are known inhibitors of active transport of ions also have no effect. It appears that lysis in this system is not brought about by increased active transport of ions into the cell but that the rabbit factor degrades or combines with some membrane component, altering permeability and resulting in increased diffusion, first of sodium and potassium ions and other small molecules, and finally of large molecules (hemoglobin) out of the cell.
Effects of Polarization of the Receptor Membrane and of the First Ranvier Node in a Sense Organ
Authors: Loewenstein W. R. , Ishiko N.
Published: May 2004

It has previously been shown that the site of production of the generator potential in Pacinian corpuscles is the receptor membrane of the non-myelinated ending, and the site of initiation of the nerve impulse, the adjacent (first) Ranvier node. Effects of membrane polarization of these sites were studied in the present work. Nerve ending and first Ranvier node were isolated by dissection, electric activity was recorded from, and polarizing currents were passed through them. All observations were done at steady levels of polarization, seconds after onset of current flow. The following results were obtained:

The amount of charge transferred through the excited receptor membrane is a function of the electrical gradients across the membrane. The generator potential in response to equal mechanical stimuli increases with resting potential of the receptor membrane. The refractory state of the generator potential is not affected by polarization.

The electrical threshold for impulse firing at the first Ranvier node (measured by the minimal amplitude of generator potential which elicits a nodal impulse) is nearly minimal at normal resting potential of the node. Both, hyperpolarization and depolarization lead to a rise in nodal threshold.

For any level of polarization of nodal and receptor membrane, the threshold for production of impulses by adequate (mechanical) stimulation appears determined by the generator potential-stimulus strength relation and by the electrical threshold of the node.
The Efflux of Potassium from Electroplaques of Electric Eels
Authors: Whittam R. , Guinnebault M.
Published: May 2004

1. The movement of labeled potassium ions has been measured across the innervated membranes of single isolated electroplaques, obtained from the organ of Sachs of Electrophorus electricus, mounted in an apparatus which allowed a separate washing of the two membranes.

2. Equations have been derived for a 3 compartment system in series in which tracer from a large pool in one outer compartment is collected in the other outer compartment. The amount of unlabeled ion in the middle compartment may be calculated and also the fluxes across the two membranes.

3. The flux of potassium across the innervated membranes of resting cells in a steady state was between 700 to 1000 µµmoles/cm.2/sec. and was unaffected by d-tubocurarine.

4. Direct stimulation of electroplaques with external electrodes caused an increase in the efflux of potassium from the innervated membrane of 5 to 8 µµmoles/cm.2/impulse, which was unaffected by d-tubocurarine; no change occurred in the efflux across the non-innervated membrane.

5. It is concluded that the discharge of electroplaques is accompanied by a small outward movement of potassium ions across the innervated membrane of the same order of magnitude as that found on excitation of squid giant axons. The data show a basic similarity of potassium movements across these two entirely different types of conducting membranes and suggest that this phenomenon may be a general feature of bioelectric currents propagating an action potential.
Determination of Equivalent Pore Radius for Human Red Cells by Osmotic Pressure Measurement
Authors: Goldstein David A. , Solomon A. K.
Published: May 2004

A new method has been developed to measure the equivalent pore radius in cellular membranes, and has been applied to human red cells. When red cells are suddenly introduced into a non-isosmolar concentration of non-lipid-soluble non-electrolyte molecules, water will enter or leave the cell. The rate of cell swelling or shrinking is determined and extrapolated to zero time to give the initial rate of volume change. By suitable adjustment of the concentration of the external solution the initial rate may be brought to zero. The transient equilibrium concentration, determined by interpolation from experimental data, gives a measure of Staverman's reflection coefficient, σ. The zero time method has enabled us to determine σ for nine permeant molecules. σ is directly related to the equivalent pore radius; the experimental data lead to a value of 4.2 Å for the equivalent pore radius in man, in good agreement with the previous figure of 3.5 Å given by Paganelli and Solomon. The zero time method offers a number of advantages over previous methods for determination of this parameter. It requires no measurement of the rate of water entrance into the cell, and is essentially independent of the kinetics of cell swelling. It may be applied to a variety of living cells so that many additional membranes may now be characterized in terms of their equivalent pore radius.
The Mechanochemistry of Muscular Contraction
Authors: Carlson Francis D. , Siger Alvin
Published: May 2004

The dependence of PC1 and ATP1 dephosphorylation on the number of isometric twitches in the iodoacetate-nitrogen-poisoned muscle has been examined. There is no net dephosphorylation of adenosinetriphosphate. PC dephosphorylation varies linearly with the number of twitches and produces equivalent amounts of C1 and P1i.1 Iodoacetate concentrations which block the enzyme, creatine phosphokinase, render the muscle non-contractile. A value of 0.286 µmole/gm. for the amount of PC split per twitch is obtained which gives a value of -9.62 kcal./mole for the "physiological" heat of hydrolysis of PC in agreement with expectations based on thermochemical data. In a single maximal isometric twitch it is estimated that 2 to 3 PC molecules are dephosphorylated per myosin molecule, or 1 per actin molecule. The results support the view that under the conditions of these experiments PC dephosphorylation is the net energy yielding reaction. The in vivo stoichiometry of the mechano-chemistry of contraction revealed by these studies on the one hand, and the known stoichiometry of actin polymerization and its coupling to the creatine phosphokinase system on the other are strikingly similar and strongly suggest that the reversible polymerization of actin is involved in a major way in the contraction-relaxation-recovery cycle of muscle.
Studies on the Carrier Function of Phosphatidic Acid in Sodium Transport
Authors: Hokin Lowell E. , Hokin Mabel R.
Published: May 2004

Incubation of slices of the salt gland of the albatross with acetylcholine, which is the physiological secretogogue for this tissue, led to a 13-fold increase in the rate of incorporation of P32 into phosphatidic acid and a 3-fold increase in the incorporation of P32 and inositol-2-H3 into phosphoinositide. The incorporation of P32 into phosphatidyl choline and phosphatidyl ethanolamine was increased relatively slightly or not at all. Respiration was doubled. The "phospholipid effect" occurred in the microsome fraction, which is known to contain fragments of the endoplasmic reticulum. The enzymes, diglyceride kinase and phosphatidic acid phosphatase, which catalyze the stimulated turnover of phosphatidic acid in brain cortex, were also found in highest concentration in the microsome fraction. The phosphatides which respond to acetylcholine are bound to protein in the membrane. On the basis of these findings it appears that phosphatidic acid and possibly phosphoinositide participate in sodium transport. A scheme, termed the phosphatidic acid cycle, is presented as a working hypothesis, in which the turnover of phosphatidic acid in the membrane, catalyzed by diglyceride kinase and phosphatidic acid phosphatase, functions as a sodium pump.
Tracer Exchange vs. Net Uptake of Glucose through Human Red Cell Surface
Authors: LeFevre P. G. , McGinniss G. F.
Published: May 2004

Previous kinetic studies of net sugar movements through the human erythrocyte surface (in response to concentration gradients) have led to postulation of a special "carrier" system for transfer of monosaccharides in these cells. But alternatively some sort of non-specific depression of cell permeability at high sugar concentrations has been suggested as a possible basis for the saturation kinetics and the competitive phenomena observed. New theoretical calculations show that these two interpretations predict entirely different orders of magnitude for the relative rate of tracer glucose exchange at such high sugar levels. Therefore, the speeds of gross chemical equilibration and of tracer glucose equilibration were compared by means of serial analyses on quickly separated cells and media, in thick red cell suspensions. Glucose was first added to glucose-free suspensions, and its entry into the cells followed; then C14-glucose was added after attainment of chemical equilibrium, and the tracer equilibration similarly followed. The speed of the tracer movement in relation to the speed of net uptake was on the order of 50 to 100 times greater than would be found in an uncomplicated diffusion process, regardless of what depressant effect might be occasioned by the high sugar levels. In contrast, the comparative rates observed are predicted by the previously proposed facilitated-diffusion mobile-carrier model for monosaccharide transfer, if the glucose-carrier complex is assigned a dissociation constant (at 20°C.) in the neighborhood of 1 mM.
The Effects of Acetylcholine on the Turnover of Phosphatidic Acid and Phosphoinositide in Sympathetic Ganglia, and in Various Parts of the Central Nervous System in Vitro
Authors: Hokin Mabel R. , Hokin Lowell E. , Shelp Weldon D.
Published: May 2004

The effect of acetylcholine on the incorporation of P32 into the individual phosphatides in slices of various structures of the nervous system has been studied. There was a marked stimulation of P32 incorporation into phosphoinositide and phosphatidic acid, but not into phosphatidyl choline and phosphatidyl ethanolamine, in the cat stellate and celiac ganglia in vitro. Acetylcholine stimulated P32 incorporation into certain phosphatides, primarily phosphoinositide and phosphatidic acid, in several structures of the cat and guinea pig brain; there was little or no effect of acetylcholine on phosphatide turnover in the inferior corpora quadrigsemina and cerebellar cortex. The suggestion is made that the phospholipid effect can best be explained as being concerned with the active transport of sodium ions out of the cell across the postsynaptic membrane of cholinergic neurons in response to acetylcholine.
The Rate of Oxygen Uptake of Quiescent Cardiac Muscle
Authors: Cranefield Paul F. , Greenspan Kalman
Published: May 2004

The rate of oxygen uptake of quiescent papillary muscle of the cat heart has been determined in a flow respirometer with the use of the oxygen electrode. The apparent rate of oxygen uptake as a function of the diameter of the muscle was also determined. It was found that papillary muscles from cat hearts use oxygen at a rate of 2.84 (microliters/mg. wet weight)/hour at a temperature of 35°C. Such muscles can be adequately supplied by diffusion when their surface is uniformly exposed to an atmosphere containing 95 per cent oxygen only if their diameter is 0.64 mm. or less. Papillary muscles from kitten hearts use oxygen at a rate of 4.05 (microliters/mg. wet weight)/hour at a temperature of 35°C. Such muscles can be adequately supplied by diffusion when their surface is uniformly exposed to an atmosphere containing 95 per cent oxygen only if their diameter is 0.53 mm. or less. If the muscles are small enough to be adequately supplied with oxygen by diffusion, the rate of oxygen uptake does not increase when the muscle is stretched.
The Surface of the Washed Human Erythrocyte as a Polyanion
Authors: Seaman G. V. F. , Heard D. H.
Published: May 2004

The electrokinetic behaviour of normal erythrocytes is compared with that of trypsin-, N-bromosuccinimide-, and tosyl-treated erythrocytes. Reduction in the net negative charge with reduction in ionic strength of the suspending medium and also on treatment with N-bromosuccinimide and trypsin is discussed using a porous non-rigid polyanion as a model for the periphery of the cell membrane.

It is deduced from the equivalent binding of chloride and thiocyanate ions and the absence of any effect on treatment of red cells with tosyl chloride, that normal, N-bromosuccinimide- and trypsin-treated cells are polyanionic in character.

Reduction in erythrocyte charge on treatment with N-bromosuccinimide or trypsin is probably not due to the removal of phosphate groups from the interface, nor to physical adsorption of N-bromosuccinimide or trypsin. The charge reduction is probably produced by bond fission with possibly a net disappearance of carboxyl groups from the electrophoretic plane of shear either by loss from, or reorientation of, the membrane. The loss or reorientation of material associated with these carboxyl groups does not lead to any basic change in the character of the surface of the cell, nor to any obvious structural instability. The biconcave discoid form is maintained and there is no significant hemolysis of the erythrocytes even after contact with a solution of trypsin for 24 hours.
The Biological Mechanisms of Air Ion Action
Authors: Krueger Albert P. , Smith Richard F. ,   with the technical assistance of Eddie Reed
Published: May 2004

Negative air ions are shown to decrease 5-hydroxytryptamine concentrations in extirpated strips of rabbit trachea and in the respiratory tracts of living mice. An initial exposure of guinea pigs to (-) air ions causes a transient rise in urinary 5-hydroxyindoleacetic acid excretion which is not observed upon subsequent exposures.

These findings are compatible with the hypothesis advanced earlier that (-) air ion effects depend on the ability of (-) ions to accelerate enzymatic oxidation of 5-hydroxytryptamine.
Osmotic Flow of Water across Permeable Cellulose Membranes
Authors: Durbin Richard P.
Published: May 2004

Direct measurements have been made of the net volume flow through cellulose membranes, due to a difference in concentration of solute across the membrane. The aqueous solutions used included solutes ranging in size from deuterated water to bovine serum albumin. For the semipermeable membrane (impermeable to the solute) the volume flow produced by the osmotic gradient is equal to the flow produced by the hydrostatic pressure RT ΔC, as given by the van't Hoff relationship. In the case in which the membrane is permeable to the solute, the net volume flow is reduced, as predicted by the theory of Staverman, based on the thermodynamics of the steady state. A means of establishing the amount of this reduction is given, depending on the size of the solute molecule and the effective pore radius of the membrane. With the help of these results, a hypothetical biological membrane moving water by osmotic and hydrostatic pressure gradients is discussed.
Interactions of Veratrum Alkaloids, Procaine, and Calcium with Monolayers of Stearic Acid and Their Implications for Pharmacological Action
Authors: Shanes Abraham M. , Gershfeld Norman L.
Published: May 2004

The interactions of veratridine, cevadine, veracevine, and veratramine with monolayers of stearic acid show marked differences. Veratridine and cevadine, at concentrations that are known from potential, ionic flux, and other measurements to affect living membranes, react strongly with the film and appear to cause an "interfacial dissolution" whereby both the alkaloid and the stearate leave the surface. Veracevine at the same concentration does not interact with the film. The veratramine reaction is weak, much like that of the local anesthetic procaine. The veratridine and cevadine effects are antagonized by 10-3 M Ca++, low pH, and 3.7 and 7.4 x 10-3 M procaine. These differences among the veratrum alkaloids and the antagonisms parallel effects observed in living systems. Such parallelism suggests that similar physical interactions are involved in the stearate film and in natural membranes.
True Anomalous Osmosis in Multi-Solute Model Membrane Systems
Authors: Grim Eugene , Sollner Karl
Published: May 2004

The transport of liquid across charged porous membranes separating two electrolytic solutions of different composition consists of both a normal and an anomalous osmotic component. Anomalous osmosis does not occur with electroneutral membranes. Thus, with membranes which can be charged and discharged reversibly, normal osmosis can be measured with the membrane in the electroneutral state, and normal together with anomalous osmosis with the membrane in a charged state, the difference between these two effects being the true anomalous osmosis. Data are presented on the osmotic effects across an oxyhemoglobin membrane in the uncharged state at pH 6.75 and in two charged states, positive at pH 4.0 and negative at pH 10.0, in multi-solute systems with 0.2 and 0.4 osmolar solutions of a variety of electrolytes and of glucose against solutions of other solutes of the same, one-half, and twice these osmolarities. In the simpler systems the magnitude of the true anomalous osmosis can be predicted semiquantitatively by reference to appropriate single-solute systems. In isoosmolar systems with two electrolytic solutions the anomalous osmotic flow rates may reach 300 µl./cm.2 hr. and more; systems with electrolytic solutions against solutions of glucose can produce twice this rate. These fluxes are of the same order of magnitude as the liquid transport rates across such living structures as the mucosa of dog gall bladder, ileum, and urinary bladder.
Inotropic Effects of Trains of Impulses Applied during the Contraction of Cardiac Muscle
Authors: Brady A. J. , Abbott B. C. , Mommaerts W. F. H. M.
Published: May 2004

The application of a train of supramaximal stimuli during the absolute refractory period of a cardiac muscle preparation has two effects: a depression of the contraction during which it is applied, and a large potentiation of subsequent contractions. The former is ascribed to a direct effect upon the cell membrane, and is an indication of the continued control of the contractile event by this membrane. The latter is explained as a sudden liberation of norepinephrine by a stimulation of embedded nerve elements, which norepinephrine then distributes itself through the tissue and finally diffuses away.
Investigations of the Electrical Properties of Cardiac Muscle Fibres with the Aid of Intracellular Double-Barrelled Electrodes
Authors: Johnson Edward A. , Tille J.
Published: May 2004

Current has been passed through the cell membrane of muscle fibres of the isolated rabbit right ventricle with the aid of intracellular double-barrelled microelectrodes. Two types of muscle fibres were distinguished which are called P and V fibres. The relation between the intensity of a hyperpolarising current applied during the rising phase and the maximum amplitude of the action potential was different in these fibres. For P fibres the relation was essentially linear over most of the range of currents used. For V fibres the change in maximum action potential amplitude was either negligible or did not appear until a certain value of hyperpolarising current was reached. This behaviour of V fibres can be understood if a drop in polarisation resistance occurs during the rising phase and is of such short duration that the polarisation resistance has returned to its resting value before the crest of the action potential is reached. P fibres have an estimated mean resting polarisation resistance of (106 ± 13) K ohms, and a rheobase current strength of (0.08 ± 0.02) µa. In V fibres the resting polarisation resistance was (47 ± 29) K ohms and the rheobase current strength (0.47 ± 0.28) µa.
Shape and Volume Changes in Frog Erythrocytes Following Ultraviolet Radiation
Authors: Maroney S. P.
Published: May 2004

Frog erythrocytes in Ringer's solution were exposed to ultraviolet radiation and then followed in camera lucida drawings for changes in shape and dimension. Cell thickness was found to increase while cell width remained constant throughout the period prior to hemolysis. The cell shortened and bulged at the ends during the middle third of the prolytic period while a region around the cell center remained constricted. When this constricted region gave way, the cell became spherical and hemolyzed. Cell volume as calculated from the cell's dimensions increased linearly with time throughout the prolytic period to hemolysis then dropped rapidly to a constant value somewhat higher than the original cell volume. These changes in shape and volume are consistent with a colloid osmotic type of hemolysis but with other factors acting to limit the rate of swelling and the forms assumed during the swelling process. The relationship between the time of hemolysis and the cell surface area exposed to the ultraviolet is discussed as it applies to the site of ultraviolet damage.
Quantitative Studies of White Matter
Authors: McDougal D. B. , Schulz D.W. , Passonneau J.V. , Clark J. R. , Reynolds M. A. , Lowry O. H.
Published: May 2004

Total lipid and six enzymes closely related to the metabolism of glucose-6-phosphate have been measured in ten tracts of the rabbit. Lipid content appears to be a valid indicator of the degree of myelination. Heavily myelinated tracts have much larger amounts of glucose-6-phosphate dehydrogenase than lightly myelinated ones but there is no corresponding difference in 6-phosphogluconate dehydrogenase. In fact the ratios between the two enzymes were found to vary over a ninefold range. Hexokinase is found in largest amounts in tracts with relatively little lipid, and this tends to be true for phosphofructokinase as well. The fibrillar layer of olfactory bulb is exceptional with regard to both enzymes, and to glucose-6-phosphate dehydrogenase. The enzymes are present in amounts which are more than adequate to support glucose metabolism at a rate commensurate with the known rates of O2 uptake by various tracts. The distribution of some of the enzymes is compatible with the notion that the nodes of Ranvier are regions of high metabolic activity. A simple algebraic relationship is found to hold fairly well for the distribution of four of the enzymes among the tracts.
The Photoactivated Relaxation of Smooth Muscle of Rabbit Aorta
Authors: Furchgott R. F. , Ehrreich S. J. , Greenblatt E.
Published: May 2004

Smooth muscle of strips of rabbit aorta, placed in a state of active tonic contraction by addition of a stimulating drug, relaxes during exposure to light. The relaxation is reversible. The extent of relaxation produced by a standard exposure depends on the preexposure level of active contraction but not on the nature of the stimulating drug used to produce contraction. With strips brought to an intermediate level of contraction, the degree of relaxation (steady state levels) is a rectangular hyperbolic function of radiation intensity. The kinetics of the relaxation process during irradiation and the recovery process following irradiation are consistent with the hypothesis that the primary photoactivated material initiates a reaction or reactions leading to a product which inhibits some process involved in the production of active contraction. The photorelaxation does not require the presence of oxygen. It is potentiated by reducing the temperature of the aortic strip. The action spectrum of the photorelaxation shows relatively low effectiveness at wavelengths above 450 mµ. The effectiveness increases markedly and progressively as the wavelength is lowered below 450 mµ, reaching a peak at 310 mµ. A deep trough occurs at 280 mµ. However, both peak and trough probably result from internal filtering due to absorption by proteins in the aortic strip. It is surmised that if a correction could be made for this internal filtering, the action spectrum would rise continuously down to wavelengths at least as low as 250 mµ.
The Secretion of Oxygen into the Swim-bladder of Fish
Authors: Wittenberg Jonathan B. , Wittenberg Beatrice A.
Published: May 2004

Toadfish, Opsanus tau, L., were maintained in sea water equilibrated with gas mixtures containing a fixed proportion of oxygen and varying proportions of carbon monoxide. The swim-bladder was emptied by puncture, and, after an interval of 24 or 48 hours, the newly secreted gases were withdrawn and analyzed. Both carbon monoxide and oxygen are accumulated in the swim-bladder at tensions greater than ambient. The ratio of concentrations, carbon monoxide (secreted): carbon monoxide (administered) bears a constant relation to the ratio, oxygen (secreted): oxygen (administered). The value of the partition coefficient describing this relation is (α = 5.44). The two gases are considered to compete for a common intracellular carrier mediating their active transport. The suggestion is advanced that the intracellular oxygen carrier is a hemoglobin. Comparison of the proportions of carboxy- and oxyhemoglobin in the blood with the composition of the secreted gas proves that the secreted gases are not evolved directly from combination with blood hemoglobin. The suggestion is advanced that cellular oxygen secretion occurs in the rete mirabile: the rete may build up large oxygen tensions in the gas gland capillaries. It is suggested that the gas gland acts as a valve impeding back diffusion of gases from the swim-bladder.