Favour Of Sodium Research Articles

L-antigen and active potassium transport in HK and LK red cells of barbary sheep ( Ammotragus lervia)

1. 1. The potassium concentration in red cells of 21 Barbary sheep showed a bimodal distribution, with five animals of LK type (K + cone. 30–45 mM) and 16 of HK type (K + conc. 80–95 mM). 2. 2. Evidence is presented that both L p and l 1antigens are present on LK Barbary sheep red cells. 3. 3. Active K +transport in LK Barbary sheep red cells was stimulated 3–5 fold by sheep and goat anti-L. 4. 4. Active K + transport in HK Barbary sheep red cells was higher than in LK red cells. Five out of six HK animals tested showed no stimulation of active K + transport with anti-L. One HK animal (2BA2) showed some stimulation of active K + transport, and also absorbed some anti-L from antisera, suggesting that L p antigen is present on these red cells. 5. 5. Ouabain-sensitive ATPase in membranes from HK and LK Barbary sheep red cells showed kinetics characteristic of HK and LK membranes of domestic goats and sheep; the ATPase of LK Barbary sheep membranes sensitized with anti-L was stimulated 2-fold due to an alteration in the internal sodium and potassium affinities in favour of sodium.

Ecophysiology of Salt Excretion in Aeluropus litoralis (Graminae)

AbstractVarious aspects of salt excretion from leaves of Aeluropus were investigated. Salt excretion exhibited an optimum‐type of curve when measured against external salt concentration, while sodium content of the leaves increased linearly. The ‘relative excretion’, i.e. rate of excreted ions: change in leaf ion content, was maximal in the low salt concentration range, and decreased when external sodium chloride concentration increased. Concentration of the excreted droplets was higher than the external concentration when the leaves were exposed to low salt concentrations in the medium, but the reverse occurred when the external salt concentrations were high. The excretion process was sensitive to water‐stress conditions, caused either by high external salt concentrations or by exposure to dry atmosphere. A considerable fraction of the leaf sodium content in salt‐treated leaves was only slightly available for excretion. Salt excretion in Aeluropus was enhanced by light. Such enhancement was indirect and is attributed to the increase of salt transport via transpiration stream.Selectivity of the salt‐excretion mechanism is in favour of sodium and against potassium. On the other hand, potassium has a high affinity for the accumulation systems within the leaves. The ecological significance of the results is discussed.