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At least 19 recordsLinked to original sources
PubMed1980

Evidence of voltage-induced channel opening in Na/K ATPase of human erythrocyte membrane.

Previous studies have shown that human erythrocytes when subjected to a high voltage pulsation, in the microsecond time range, lysed in an isotonic medium. The hemolysis was the result of the colloid osmotic swelling, which, in turn, was caused by the voltage perforation of the red cell membranes. In this work we demonstrate that in a low ionic medium at least 35% of the pores was related to the opening of Na+/K4 ATPase channels. The membrane conductance generated by the externally applied electric field could be partially blocked by a specific inhibitor, ouabain, or by a specific cross-linkin g reagent, Cu++-phenanthroline, of the ATPase. The effect of ouabain was saturable and had a mid-point of saturation at 0.15 microM. This value agrees with the physiological inhibition constant of the drug. K+ ion in the external medium suppressed the effect of ouabain, as has also been demonstrated n physiological studies. Experiment presented in this communicaton also suggests that the Na+/K+ ATPase was not perforable in a high ionic medium, and that a large fraction of the voltage-induced pores occurred at as yet unidentified sites.

Erythrocyte Membrane↗
PubMed1980

Characterization of bone marrow stromal cells in suspension and monolayer cultures.

Aspirated marrow fragments from healthy adult baboons were cultured in a simple liquid suspension tissue culture system. During the incubation period, haemopoietic cells were discharged from the fragments and settled to the floor of the culture vessels, thus allowing a separation of marrow stromal elements, retained within the fragments. Cells associated with the marrow stroma in vitro were of four main types: adipocytes, macrophages, plasma cells and unidentified lipid-laden cells related to fibroblasts. These last cells were capable of DNA synthesis in vitro, and were morphologically and functionally distinguishable from typical marrow macrophages. Macrophages were characterized by their phagocytic properties. Plasma cells were capable of prolonged survival and immunoglobulin output in vitrol. In monolayer cultures of disaggregated fragment cell suspensions, the lipid-laden stromal cells rapidly assumed fibroblast-like morphology. Fibroblastic proliferation to confluent monolayers was seen within a few days. Plasma cells reorientated themselves around these cells to form rosettes, and bridge communicatons between the two cell types were seen frequently. Plasma cell immunoglobulin output rate per cell appeared to be potentiated by this association.

Animals↗