Search PubMed⌕ Search

Biomedical subjects

G N Ling

Publications and source records attributed to G N Ling.

106 records · Page 6Linked to original sources
PubMed1971

Metabolic cooperative control of electrolyte levels by adenosine triphosphate in the frog muscle.

This study examines the effects of metabolic inhibitors on the content of cellular K, Na, and adenosine triphosphate (ATP). ATP and K are seen to fall in the inhibited tissues. The ATP content is correlated with the K content. The role of ATP is examined according to a recent biophysical approach. It is suggested that ATP may control the electrolyte levels by inducing conformational changes in the cytoplasmic proteins.

Adenosine Triphosphate↗
PubMed1970

Studies on ion distribution in living cells. II. Cooperative interaction between intracellular potassium and sodium ions.

New steady levels of K(+) and Na(+) ion in frog sartorius muscle were reached in 72 hr at 25 degrees C in environments containing 100-mM Na(+)-ion and K(+)-ion concentrations varying from near zero to 10 mM. These steady levels follow a pattern predicted by a cooperative adsorption isotherm presented in 1964. From a total of 13 sets of experiments carried out over a five year period, the average concentration of adsorption sites is 109 mumoles/g of fresh cells. The average intrinsic equilibrium constant for the Na --> K exchange is 135, and the average free energy of nearest neighbor interaction is 0.54 kcal/mole. These values are in good agreement with those obtained by Jones and Karreman from studies on canine carotid arteries.

Adsorption↗
PubMed1970

Diphosphoglycerate and inosine hexaphosphate control of oxygen binding by hemoglobin: a theoretical interpretation of experimental data.

A theoretical equation is presented for the control of cooperative adsorption on proteins and other linear macromolecules by hormones, drugs, ATP, and other "cardinal adsorbents." With reasonable accuracy, this equation describes quantitatively the control of oxygen binding to hemoglobin by 2,3-diphosphoglycerate and by inosine hexaphosphate.

Adsorption↗
PubMed1969

Potassium ion: is the bulk of intracellular K+ adsorbed?

When a major portion of the intracellular K(+) in frog muscle is reversibly replaced by Na(+), the extra Na(+) gained by the cells does not show the nuclear magnetic resonance signal that free Na(+) does. The data contradict the membrane theory but are in accord with the concept that the bulk of intracellular K(+) is adsorbed.

Animals↗
PubMed1967

The extracellular space of voluntary muscle tissues.

The volume occupied by the extracellular space has been investigated in six types of voluntary muscles: sartorius (frog), semitendinosus (frog), tibialis anticus longus (frog), iliofibularis (frog), rectus abdominis (frog), and diaphragm (rat). With the aid of four types of probe material, three of which are conventionally employed (inulin, sorbitol, sucrose) and one of which is newly introduced (poly-L-glutamate), and a different experimental method, we have demonstrated that the "true" extracellular space of frog sartorius, semitendinosus, tibialis anticus longus, and iliofibularis muscle and of rat diaphragm muscle is equal to, or probably less than, 8-9% (v/w) of the tissue. The frog rectus muscle shows a somewhat higher ceiling value of 14%.

Animals↗
PubMed1966

Studies on ion accumulation in muscle cells.

A comparison is made between the quantitative predictions of equilibrium ionic distribution in living cells according to the membrane theory (Donnan equilibrium) and according to the association-induction hypothesis. This comparison shows that both theories predict competitive effects of one permeant ion on the equilibrium concentration of another permeant ion; but within the limit of experimental accuracy only the association-induction model predicts quantitatively significant specific competition of one specified ion with the accumulation of another specified ion. The equilibrium distributions of K(+), Rb(+), and Cs(+) ions in frog sartorius muscle were studied and quantitatively significant specific competition was demonstrated; these results favor the association-induction hypothesis (adsorption on cell proteins and protein complexes and partial exclusion from cell water). Based on this model we estimated that at 257deg;C, the apparent association constants for K(+), Rb(+), and Cs(+) ion are 665, 756, and 488 (mole/liter)(-1). We found that the total concentration of adsorption sites (no less than 240 mmole/kg of fresh cells) agrees with the analytically determined concentrations of beta- and gamma-carboxyl groups of muscle cell proteins (260 to 288 mmole/kg).

Animals↗
PubMed1965

Studies on the ionic permeability of muscle cells and their models.

We studied the effect an alkali-metal ion exercised on the rate of entry of another alkali-metal ion into frog sartorius muscle cells and their models (i.e., ion exchange resin and sheep's wool). In the case of frog muscle, it was shown that the interaction fell into one of four categories; competition, facilitation, and two types of indifference. The observed pK value (4.6 to 4.7) of the surface anionic groups that combine with the alkali-metal ions suggests that they are beta- or gamma-carboxyl groups of proteins on the cell surface. The results were compared with four theoretical models which included three membrane models (continuous lipoid membrane with carrier; leaky membrane with carrier; membrane with fixed ionic sites) and one bulk-phase model. This comparison led to the conclusion that the only model that is self-consistent and agrees with all of the experimental facts is the one based on the concept that the entire living cell represents a proteinaceous fixed-charge system; this model correctly predicts all four types of interaction observed.

Animals↗