Nonionic Substances Research Articles

The effect of low ionic strength extracellular solutions on the resting potential in skeletal muscle fibers.

Intracellular measurements of the resting potential were made in fibers of the frog sartorius muscle in solutions of varying salt composition and concentration to determine the effects of low ionic strength extracellular solutions on the resting potential. Changes in the glass microelectrode tip potential in low ionic strength solutions were minimized by adding ThCl(4) to the extracellular solution. These experimental conditions allowed measurement of the relationship of the resting potential to the concentration of the salt in the extracellular solution by replacing it with the nonionic substance, sucrose. Substitution of sucrose for the extracellular NaCl produced a stable depolarization which was logarithmically related to the NaCl concentration. Substitution of sucrose for choline Cl, instead of NaCl, produced the same degree of depolarization. When Na salts of anions less permeable than chloride (Br, I, NO(3)) were used, the resting potentials in 116 mM solutions were close to those with chloride (+/-3mv). The depolarizations produced in low ionic strength solutions of these salts were significantly less than those with chloride.

CONTRACTURE COUPLING OF SLOW STRIATED MUSCLE IN NON-IONIC SOLUTIONS AND REPLACEMENT OF CALCIUM, SODIUM, AND POTASSIUM.

The development of contracture related to changes of ionic environment (ionic contracture coupling) has been studied in the slowly responding fibers of frog skeletal muscle. When deprived of external ions for 30 minutes by use of solutions of sucrose, mannitol, or glucose, the slow skeletal muscle fibers, but not the fast, develop pronounced and easily reversible contractures. Partial replacement of the non-ionic substance with calcium or sodium reduces the development of the contractures but replacement by potassium does not. The concentration of calcium necessary to prevent contracture induced by a non-ionic solution is greater than that needed to maintain relaxation in ionic solutions. To suppress the non-ionic-induced contractures to the same extent as does calcium requires several fold higher concentrations of sodium. Two types of ionic contracture coupling occur in slow type striated muscle fibers: (a) a calcium deprivation type which develops maximally at full physiological concentration of external sodium, shows a flow rate dependency for the calcium-depriving fluid, and is lessened when the sodium concentration is decreased by replacement with sucrose; (b) a sodium deprivation type which occurs maximally without external sodium, is lessened by increasing the sodium concentration, and has no flow rate dependency for ion deprivation. Both types of contracture are largely prevented by the presence of sufficient calcium. There thus seem to be calcium- and sodium-linked processes at work in the ionic contracture coupling of slow striated muscle.

An Ion-Exchange Resin Method for the Fractionation of Alcoholic Plant Extracts

DURING a study of the effect of benzimidazole on the carbon-14 labelled amino-acid metabolism in detached wheat leaves, it was found desirable to fractionate an alcoholic extract (less the chloroform-soluble substances) into acidic, basic, and non-ionic (or neutral) substances prior to any further chrormatographic analysis on filter paper. Ion-exchange resins offer a valuable means for this purpose, which may be satisfactorily achieved with a combination of cationic and anionic ion-exchangers. I have, however, experienced a considerable loss of radioactivity with such ion-exchangers as ‘Amberlite IR-120’ and ‘IR-45’ and, as a result, recovery of the radioactive compounds was never quantitative. Later it was found that a combination of ‘Dowex 50, X-8’ (200–400 mesh) and ‘AG 1 (Dowex 1)’, ‘X-10’ (200–400 mesh) in formate form made it possible to fractionate the alcoholic extract into basic, acidic, and non-ionic substances without any appreciable loss of radioactivity. (Analytical grade anion exchange resin, ‘AG 1–X 10’ (200–400 mesh), chloride form, was obtained from the California Corporation for Biochemical Research, Los Angeles 63. This resin was prepared by sizing and purifying the standard ‘Dowex’ resin of the same designation by BIO-RAD Laboratories.)

Studies on the Interaction of Surface Films with Solute in Solution. IV. Effect of Congo Red Dissolved in Aqueous Substrate upon the Monolayers of Octadecylamine, Cetyl Alcohol, Ethyl n-Hexadecyl Ether, Ethyl Stearate and Cholesterol

Abstract Effect of dissolved Congo red upon the monolayers of octadecylamine, cetyl alcohol, ethyl n-hexadecyl ether, ethyl stearate and cholesterol spread on the substrate containing the dye has been studied, under varying pH of the solution. It has been observed generally that all monolayers expanded when they were spread on aqueous solution, the pH of which was in such a region that the molecules of dye were almost in zwitterion form. Dipolar and van der Waals’ attraction were tentatively postulated to explain the nature of the cohesive force by which the molecules of dye were bond together so that the colloidal aggregates were formed in the solution. The expansion of the monolayer can be accounted for by the binding of the aggregate to film materials. This explanation could successfully be applied to the films of such nonionic substance as cetyl alcohol, ethyl n-hexadecyl ether and ethyl stearate. The largest expansion of the monolayer of octadecylamine was observed when the substrate containing dye showed acidity so that the molecules of dye were partly of negative charge while those of octadecylamine were of positive charge. In this case we had better take account of the possibility of ion-ion attraction between octadecylamine and dye, in addition to the forces which appeared in the cases of nonionic substances.

Use of ion exchange resins with nonaqueous and mixed solvents

This review examines some of the recent developments in the use of synthetic ion exchangers for three types of separations: the separation of ionic substances in nonaqueous or mixed solvents, the separation of nonionic substances in nonaqueous or mixed solutions, and the separation of ionic from nonionic materials in solution.

Experiments with Ion-Selective Membranes. I. The Electrolytic Deionization of Protein-Free Whey

Summary The ionizable components can be easily and quickly removed from deproteinized whey by electrodialysis through ion-selective membranes without the loss of appreciable quantities of diffusible nonionic substances.

The ultraviolet absorption spectra of desoxypentose nucleic acid

The intensity of the ultraviolet absorption of sodium desoxypentose nucleate (SDN) in aqueous solution is lowered by the addition of salts, such as alkali halides and phosphates. SDN absorbance in sodium chloride solutions has been carefully measured and appears to vary linearly with the log of the sodium chloride concentration over a 10 5 change in salt concentration. In the absence of salt, the ultraviolet absorption of SDN solutions show strong pH dependence between pH 3 and pH 11. Aqueous SDN at pH 6.7 in the absence of added salt has an absorptivity ( k) of 25.5 and A 1cm 1% of 258 at 259 mμ (when measurements are made on concentration less than 0.01%). These values are considerably higher than previously reported. Aqueous SDN solutions in the pH range 2 to 10 have an isosbestic point at 233 m/gm. Addition of lysozyme and bovine plasma albumin to SDN solutions also result in a decrease in the ultraviolet absorption due to SDN. On the other hand, the addition of non-ionic substances such as polyvinyl alcohol, sucrose, or glycerol to aqueous SDN solutions, even in high concentrations, does not decrease its ultraviolet absorption. An explanation of these data in terms of the association of the component purine and pyrimidine groups is suggested. These results indicate that caution must be exercised in using measurements of absorption intensities in the ultraviolet for the determination of the purity of nucleic acid preparations and for the determination of the nucleic acid content of tissues and cells unless the ionic strength, pH, and Beer's Law deviation are known.

A TEST FOR DIFFUSIBLE IONS

1. The Donnan equilibrium furnishes a test for the ionic nature of any diffusible substance, since the ratio of the concentration of any ion on the two sides of a membrane must be equal to the ratio of the concentrations of any other ion of the same sign and valence, whereas a non-ionic substance would be equally distributed on both sides. 2. The distribution of trypsin inside and outside of gelatin particles has been compared to the distribution of hydrogen and chloride ions under the same conditions. 3. The ratio of the trypsin concentration in the gelatin to the concentration in the outside liquid is equal to the ratio of the hydrogen ion under the same conditions and to the reciprocal of the chloride ion ratio. 4. This result was obtained between pH 2.0 and 10.2. At pH 10.2 the trypsin is equally distributed and on the akaline side of 10.2 the ratio is directly equal to the chloride ratio. 5. Trypsin is therefore a positive monovalent ion in solutions of pH 10 to 2. It is probably isoelectric at 10.2 and a monovalent negative ion on the alkaline side of 10.2 6. Trypsin must also be a strong base since there is no evidence of any undissociated form on the acid side of pH 10.2.