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Biomedical subjects

L B KIRSCHNER

Publications and source records attributed to L B KIRSCHNER.

At least 19 recordsLinked to original sources
PubMed1964

TURNOVER OF PHOSPHATIDIC ACID AND SODIUM EXTRUSION FROM MAMMALIAN ERYTHROCYTES.

Phosphatidic acid (PA) from swine and beef RBCs was isolated by chromatography on silicic acid columns. It comprised about 1 per cent of the total lipid phosphate in RBCs, but was eluted nearly pure from columns. An uncharacterized inositide accounted for 5 to 10 per cent of the phosphate in the PA-containing fraction. When cells were incubated with HP(32)O(4) (=), the fraction containing PA became more radioactive than any of the other fractions obtained. However, analysis of the labeled material by paper chromatography showed that most of the P(32) was in the inositide, not in PA. With the assumption of kinetic homogeneity for cellular PA, compartmental analysis of the kinetics of tracer incorporation showed that PA turnover is 3 to 4 orders of magnitude too slow to account for sodium extrusion by these cells.

Adenosine Triphosphatases↗
PubMed1962

Sodium fluxes in the erythrocytes of swine, ox, and dog.

Sodium fluxes were measured in erythrocytes from three species of mammals. Unidirectional fluxes were slowest in swine RBCs (low sodium cells), fastest in dog RBCs (high sodium cells), and between these extremes in ox cells (intermediate level of internal sodium). In addition, efflux and influx in swine cells both correlated positively with intracellular sodium concentration between 12 to 4 microeq/ml. Tracer effluxes in swine and beef cells were separated into three components: active transport, diffusion, and exchange diffusion. The last two also contributed to influx. Transport was greater in swine cells than in beef, while the leak was similar in both. Pump to leak ratios were about 21 for swine and 3 for beef, a difference that probably accounts for the higher cell sodium in the latter. Exchange diffusion was faster in beef cells than in swine resulting in a larger tracer movement in beef. The exchange mechanism was temperature-sensitive, but was not inhibited by strophanthin. The unidirectional fluxes in canine cells were inhibited by low temperature, but they were sensibly unaffected by strophanthin. When placed in magnesium Ringer's solution (inhibits exchange diffusion in beef and swine cells) dog RBCs lost more than half of their internal sodium at a rate approximating the isotope flux in plasma or normal Ringer's solution. It was, however, not possible to separate the total tracer movement into pump, leak, and exchange.

Animals↗
PubMed1960

Permeability of frog skin to choline.

An inward movement of choline can be demonstrated across isolated skins of Rana pipiens when the outside is bathed by a saline made with choline chloride. This is in contrast to an earlier report indicating that skins of R. esculenta are impermeable to choline. The flux was very small and independent of the active transport of sodium by the skins. For most experiments choline can be used as an "inert" replacement for sodium in this prepration.

Animals↗
PubMed1960

Calcium and electric potential across the clam mantle.

An excised clam mantle develops a potential difference, shell side positive, when both surfaces are bathed by tap water or physiological saline solution. The magnitude and sign of the potential are sensitive to the calcium concentration in the bath solution. Bubbling carbon dioxide through the solution bathing the shell side increased the potential.

Animals↗
PubMed1958

The cation content of phospholipides from swine erythrocytes.

Phospholipides from swine erythrocytes were isolated and separated into four reproducible fractions. One of the fractions seems to be pure phosphatidylserine. The others are almost certainly not single compounds, although the analytical data indicate that they represent mixtures considerably simpler than the parent mixture extracted from the cells. All four fractions contained Na(+) and K(+), but very little Ca(2+). Sodium was the predominant cation in two of the fractions under all conditions although the major intracellular cation was potassium. In the other two fractions the ratio Na/K varied with the extraction procedure largely because the quantity of K(+) seemed to depend on the solvent system used. There appear to be reasons to believe that the entire system of phospholipides binds Na(+) preferentially. In addition, it was observed that the quantity of Na(+) found in the lipide extracts varied when the extrusion of Na(+) from the cells was made to vary. Both of these observations are consistent with the possibility that the phospholipides play some part in the extrusion of Na(+) from these cells.

Animals↗