PubMed Health⌕ Search

Biomedical subjects

G N Ling

Publications and source records attributed to G N Ling.

At least 55 records · Page 3Linked to original sources
PubMed1983

Only solid red blood cell ghosts transport K+, and Na+ against concentration gradients: hollow intact ghosts with K+-Na+ activated ATPase do not.

Human red blood cell ghosts, prepared by simple hypotonic lysis are filled with cytoplasmic proteins. These solid ghosts can transport K+ and Na+ against concentration gradients in the presence of ATP. In hollow red cell ghosts prepared by repeated hypotonic lysis followed by high salt wash, this ability to transport K+ and Na+ in the presence of ATP is lost even though these hollow ghost membranes remain intact and are equipped with Na+-K+ activated ATPase.

Adult↗
PubMed1983

Cooperative interaction among cell surface sites: evidence in support of the surface adsorption theory of cellular electrical potentials.

Resting potentials were studied in frog sartorius muscles equilibrated in Ringer solutions that contained various concentrations of K+. Cells in solutions that contained near-zero K+ showed a rise in potential followed by a slow decline over about 70 hours that paralleled the loss of cellular K+ in exchange for Na+. When these cells were placed in 2.5 mM K+, the re-gain of the potential occurred much more rapidly than the re-gain of cellular K+. Thus, there was no consistent relation between resting potential and concentration of intracellular K+. When cells were immersed in solutions containing 100 mM Na+ and K+ at concentrations of 2.5 mM and greater, there was a semi-logarithmic relation between potential and [K+]ex, in which potential declined as [K+]ex increased. However, when cells were equilibrated in [K+]ex below 2.5 mM, the potential peaked and then declined as [K+]ex decreased. The results are readily explained by the surface adsorption model of the cellular potential, in which the potential is determined simply by the nature of the fixed surface charges that interact with one another in a cooperative manner. The peak and decline of the potential with decreasing [K+]ex below 2.5 mM mirrors the autocooperative shift in the affinity of the surface charged sites from one that favors K+ over Na+ strongly to one that favors K+ over Na+ less strongly.

Animals↗
PubMed1983

Indifference of the resting potential of frog muscle cells to external Mg++ in the face of high Mg++ permeability.

Incubation of frog sartorius muscles for 18 hours at constant external concentrations of K+ and Na+, but with the external concentration of Mg++ varying from 1.2 to 73.2 mM, brought about no change in the resting potential which remained constant at 88 mV. Results were the same in MgCl2 as in MgSO4. However, these cells are nearly as permeable to Mg++ as they are to K+. These results contradict the membrane theory of the cellular potential but are compatible with the surface adsorption model of the cellular potential.

Animals↗
PubMed1983

Studies on the physical state of water in living cells and model systems. I. The quantitative relationship between the concentration of gelatin and certain oxygen-containing polymers and their influence upon the solubility of water for NA+ salts.

The quantitative relationships between the concentrations of solutions of gelatin, polyvinylpyrrolidone, poly(ethylene oxide), polyvinylmethylether, and poly(ethylene glycol), and their ability to reduce the solubility of water for Na citrate are presented. The data in general are in harmony with the polarized multilayer theory of protein (and polymer) dominated water in vitro and in living cells.

Citrates↗
PubMed1983

Studies on the physical state of water in living cells and model systems. II. NMR relaxation times of water protons in aqueous solutions of gelatin and oxygen-containing polymers which reduce the solvency of water for NA+, sugars, and free amino acids.

This communication reports our study of the NMR relaxation times, T1 and T2 of water protons in aqueous solutions of bovine serum albumin, gelatin, polyvinylpyrrolidone, poly(ethylene oxide), and polyvinylmethylether over a wide concentration range. In contrast to solutions of gelatin and bovine serum albumin, the T1/T2 ratio of the three synthetic polymers are close to unity over the entire range studied. When combined with earlier-reported data of water made "non-solvent" to Na salts, the present data provided the basis for calculating the T1 and T2 as well as the rotational correlation time tau c of the "non-solvent" water. It was shown that only a modest increase by a factor of about 3 of tau c is enough to produce water that is "non-solvent" for Na citrate and sulfate. The new data reconciles NMR data of living cells with the theory of the cell water given in the association-induction hypothesis. The variability of tau c of "non-solvent" water also offers explanations of apparently conflicting conclusions on the physical state of cell water from dielectric measurements.

Amino Acids↗
PubMed1983

Studies on the physical state of water in living cells and model systems. III. The high osmotic activities of aqueous solutions of gelatin, polyvinylpyrrolidone and poly (ethylene oxide) and their relation to the reduced solubility for NA+, sugars, and free amino acids.

Very high osmotic activities of concentrated aqueous solutions of gelatin, polyvinylpyrrolidone, and poly(ethylene oxide) were recorded. These observed values are far above those predictable from the molar concentrations of these polymers or those of aqueous solutions of native hemoglobin of equal concentrations. It was shown that these high osmotic activities are closely associated with the ability of the gelatin- or polymer-dominated water to exclude Na+ salts, sucrose, and glycine. Both phenomena are interpreted as reflecting the polarization of multilayers of water by the polymers enhancing the H2O to H2O interaction and also reducing the translational and rotational motional freedom of the water.

Cytoplasm↗
PubMed1983

Cold injury-induced swelling of brain and other tissues: its molecular mechanism.

Isolated mouse brain, kidney, and other tissues were incubated for from one to several days at 4 degrees C in isotonic solutions containing varying mixtures of sucrose and NaCl (or Na2SO4, LiCl, Li2SO4, MgSO4). The ischemic, cold-injured tissues swelled in proportion to the concentration of NaCl or LiCl. They swelled less in Na2SO4 and Li2SO4 and they swelled even less and/or shrank in MgSO4 or sucrose. It was shown that in the presence of about 100 mM NaCl, the degree of swelling follows inversely the level of ATP present in the cells. The data were interpreted using the theory of cell swelling based on the association-induction hypothesis: NaCl- and LiCl-induced swelling in injured tissues and KCl-induced swelling in normal tissues, were both explained as the consequence of the dissociation of the volume-restraining effects of salt linkages among cell proteins. The depletion of ATP and the consequent increase of electron density or c-value of the fixed anionic groups turns NaCl (ineffective in causing swelling of normal tissues) into a fully effective agent for causing swelling of the injured tissues.

Adenosine Triphosphate↗
PubMed1983

Evidence that Na+ in a sulfonate ion exchange resin exists in an adsorbed state. Its significance for the interpretation of NMR data in resins and cells.

The concentrations of total Na+ and of free Na+ were measured in solutions of Na+ polystyrene sulfonate (NaPSS). Free Na+ was determined using a Na+-sensitive glass electrode having a high degree of specificity for Na+. In a 5% PSS solution, 80% or more of the Na+ was not detected by the glass electrode and was adsorbed specifically onto the anionic sulfonate groups. The degree of adsorption increased with an increase in the concentration of PSS. These results were discussed in regard to the interpretation of NMR studies of Na+ in the cross-linked PSS resins (Dowex 50) and in living cells. The results show that the quadrupolar splitting of the Na+ NMR signal is caused by specific ionic adsorption onto fixed anionic sites and not by a diffuse charge gradient extending over large distances.

Adsorption↗
PubMed1983

Studies on the physical state of water in living cells and model systems. IV. Freezing and thawing point depression of water by gelatin, oxygen-containing polymers and urea-denatured proteins.

Using a differential scanning calorimeter, we studied the freezing and thawing behavior of solutions of six globular proteins (hemoglobin, bovine serum albumin, gamma-globulin, beta-lactoglobulin, egg albumin, and protamine sulfate); gelatin; and three synthetic polymers (polyvinylpyrrolidone (PVP), polyvinylmethylether (PVME), and poly(ethylene oxide) (PEO)]. The native globular proteins in concentrations up to 50% produced no major change of the freezing temperature of the bulk phase water, or of the shape of the freezing peaks. In contrast, the synthetic polymers caused a lowering of the freezing temperature and a widening of the freezing peaks; the peaks disappeared at the highest macromolecular concentration and exothermic peaks appeared during subsequent warming (warming exothermic peak or WEX). Gelatin behaved like the three polymers and so did the globular proteins after denaturation with urea but not after denaturation with sodium dodecyl sulfate (SDS). These different patterns of freezing and thawing of solutions of native globular proteins and of SDS-denatured globular proteins, on the one hand, and of gelatin, PVP, PVME, PEO, and urea-denatured globular proteins, on the other, parallels perfectly the different abilities of these groups of substances to reduce the solvency of the water for solutes, reported earlier. The major new conclusion from this study is that the presence of macromolecules to a concentration as high as 50% does not necessarily inhibit or even delay to any appreciable extent the freezing of the bulk phase water present. On the other hand, inhibition of ice-formation does occur in the presence of macromolecules (e.g., gelatin, PVP) that cause multilayer polarization of the bulk phase water. The findings allow new evidence to be derived that the bulk of water in living cells also exists in the state of polarized multilayers.

Animals↗
PubMed1983

Studies on the physical state of water in living cells and model systems. V. The warming exothermic reaction of frozen aqueous solution of polyvinylpyrrolidone, poly(ethylene oxide), and urea-denatured proteins.

The warming exothermic peaks (WEX) first described by Luyet and coworkers in solutions of ethylene glycol, glycerol, and polyvinylpyrrolidone(PVP) was interpreted on the basis of a devitrification phenomenon, in which rapid cooling converts normal water to amorphous ice, which devitrifies on warming to the state of normal Ice I. Our present studies of the WEX phenomenon in aqueous solutions of urea-denatured proteins, PVP, PVME, and two types of poly(ethylene oxide) led us to a different conclusion: WEX is the result of a transformation of chilled water in the state of polarized multilayers to Ice I. Among the evidence for this is the fact that WEX of the polymer-water system is indifferent to the rate of cooling between 320 degrees/min. and 1.25 degrees/min. and that polymer-water systems cooled to -70 degrees C remain viscous liquids and not (solid) vitreous ice. The transformation from water dominated by PVP, PVME, and urea-denatured proteins to Ice I can occur rapidly during warming or more slowly when the chilled polymer-water systems are kept at 223 degrees K. To effect this transformation the polymers themselves must undergo movements which tend to be retarded most by the presence of bulky side chains, as in urea-denatured proteins, and least in polymers with no side chains (e.g., Polyox WSR-N750).

Animals↗
PubMed1982

The cellular resting and action potentials: interpretation based on the association-induction hypothesis.

The Hodgkin, Huxley, and Katz theories of resting and action potentials are based on the membrane theory, which holds that cell K+ and water exist in the free state. Reviewed here are these theories of cellular potential along with the results of experimental testings. Reviewed also is Ling's association-induction (AI) hypothesis, which holds that all K+ is absorbed selectively and singly on anionic protein sites and that cell water is absorbed in multilayers on extended chains of "matrix proteins." In the development of the AI model, molecular mechanisms of cell permeation and electric potentials were presented according to which the potentials are surface-adsorption phenomena. Thus they resemble those suggested by Baur rather than the membrane potentials proposed by Ostwald and Bernstein. In the present review it is shown that the AI version of the surface adsorption model can account for evidence supporting the Hodgkin, Huxley, Katz approach as well as evidence against it-including extensive recent confirmation of the absorbed state of K+ in muscle.

Action Potentials↗
PubMed1981

A unitary cause for the exclusion of Na+ and other solutes from living cells, suggested by effluxes of Na+, D-arabinose, and sucrose from normal, dying, and dead muscles.

1. The effluxes of labeled Na+, D-arabinose, and sucrose from normal muscle and muscle poisoned with low concentrations of iodoacetate were studied. The procedure involved repeated loading with isotope, followed by washing of the same muscle while still normal and at different states of dying. 2. The rates of Na+ efflux in both the fast and slow fraction remained either quite constant or showed some unpredictable, minor fluctuations. This was true for both Na+ and the two sugars studied, confirming earlier conclusions that the steady levels of these solutes were not maintained by pumps. 3. In all cases studied, the efflux curves showed at least two fractions. It is the fast-exchanging fraction that steadily and consistently increased in magnitude as the muscles were dying, until finally the concentration of solute in this fraction reached and sometimes surpassed the labeled solute concentrations in the original labeled solutions in which the muscles were equilibrated. The slow fractions showed only a transient increase or none at all. These observations show that it is the fast fraction that represents solute dissolved in cell water and rate-limited by passage through the cell surface and that the partial exclusion of Na+ and the sugars have a unitary cause--a reduced solubility in the cell water which in the presence of ATP exists in the state of polarized multilayers.

Animals↗