Cation transport in oxidant-stressed human erythrocytes: heightened N-ethylmaleimide activation of passive K+ influx after mild peroxidation.

Normal and chronically dehydrated (hereditary xerocytosis) human red cells were subjected to mild peroxidative treatment (315 microM hydrogen peroxide (H2O2), 15 min) in the presence of azide. The subsequent expression of passive (ouabain-resistant) K+ transport activities was analyzed by measurement of 86Rb+ influx. Peroxidation of normal red cells did not affect basal K+ transport activity, but the increment in K+ influx elicited by 0.

The role of membrane protein sulfhydryl groups in hydrogen peroxide-mediated membrane damage in human erythrocytes.

The formation of spectrin-hemoglobin complex following treatment of red cells with hydrogen peroxide (H2O2) has previously been shown to be associated with alterations in cell shape, decreased membrane deformability and increased recognition of modified cells by anti-IgM immunoglobulin in a phagocytic assay by monocytes. Prior treatment with carbon monoxide completely inhibited the H2O2-associated membrane changes, indicating a role for oxidized hemoglobin in the complex formation. Also, in a cell-free system, blockage of sulfhydryl (SH) groups on purified spectrin by N-ethylmaleimide significantly reduced the complex formation, suggesting a role for SH groups of spectrin in crosslinking process.

Ileal mucosal cyclic AMP and Cl secretion: serosal vs. mucosal addition of cholera toxin.

Changes in ion transport and cyclic AMP (cAMP) concentration produced by addition of cholera toxin to the serosal side of isolated rabbit ileal mucosa (CTs) were compared to the changes produced by addition to the mucosal side (CTm). CTs increased short-circuit current (SCC) as did CTm but it did so more slowly. CTs, unlike CTm, did not significantly decrease electrical conductance.

Catecholamine effects on cyclic AMP levels and ion secretion in rabbit ileal mucosa.

Effects of catecholamines on cyclic AMP (cAMP) levels and ion fluxes were examined in isolated rabbit ileal mucosa. The base-line cAMP level was unaffected by epinephrine (Epi), norepinephrine (Norepi), and isoproterenol. The theophylline-augmented cAMP level was decreased slightly be Epi in one series of experiments but not in another.