Studies on potassium permeability changes in human erythrocytes

Zusammenfassung Die durch Monojodessigsäure und Purinnukleoside erzeugte K-Permeabilitätsänderung der Erythrocyten konnte durch Präinkubation mit Nukleosiden beeinflusst werden. Die Geschwindigkeitsänderung des K-Verlustes ist wahrscheinlich die Folge einer 2,3-Diphosphoglycerinsäure-Stoffwechselveränderung.     

Effect of insulin on potassium transfer in human and chicken erythrocytes

Riassunto La conservazione al freddo degli eritrociti umani e di pollo per 6 giorni causa una fuoruscita di potassio dai globuli. Parte del potassio rientra nelle cellule durante incubazione a 37° C.La uabaina blocca questo fenomeno. L'insulina non ha effetto significativo nè sull'assunzione di potassio da parte del globulo rosso, nè sull'azione bloccante della uabaina.

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Aided by a grant from the Chicago Heart Association.

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Trainee, Diabetes Teaching Grant No. 2A-5102, National Institute of Arthritis and Metabolic Diseases, Public Health Service.     

Effect of barbiturate on Mg++-dependent ATPase in human erythrocytes

Zusammenfassung Die Aktivität der Mg⁺⁺-abhängigen ATPase in der Membran menschlicher Erythrozyten ändert sich in Anwesenheit von Barbiturat (Barbital der Firma Spofa). 10 mM Barbiturat stimuliert das Enzym, während 100 mM zu einem Verlust der enzymatischen Aktivität führt. Bei Erythrozyten, deren Enzym mit Saponin stimuliert wurde, ist der Einfluss von 10 mM Barbiturat statistisch nicht signifikant. 100 mM Barbiturat hat eine hemmende Wirkung.     

The pH-dependence of glucose transport inhibition by local anesthetics in human erythrocytes

Summary Local anesthetics vary in inhibition of glucose transport in human erythrocytes at different pH-values in the incubation media.The authors thank Dr G. Zimmer for valuable discussions. The work was supported by the Deutsche Forschungsgemeinschaft.     

Phenothiazine derivatives as inhibitors of the glucose oxidative pathway in human erythrocytes

Zusammenfassung Phenothiazinabkömmlinge unterscheiden sich in ihrer Wirksamkeit als Hemmstoffe im oxydativen Glukosestoffwechsel in menschlichen Erythrozyten. Kombiniert man verschiedene Phenothiazinderivate, so erhält man einen mittleren Hemmungsgrad, der zwischen jenen liegt, die man bei Anwendung der einzelnen Wirkstoffe für sich allein erhalten würde. Somit erscheint es nicht wahrscheinlich, dass Hemmung des oxydativen Glukosestoffwechsels die prinzipielle Wirkungsweise der Phenothiazinabkömmlinge darstellt.     

Hemagglutination of neuraminidase-treated human erythrocytes byLeishmania enriettii infected guinea-pig sera

Summary Sera from guinea-pigs infected with the protozoan parasiteLeishmania enriettii showed higher hemagglutination (HA) titres for neuraminidase treated human erythrocytes than those of normal guinea-pig sera. This HA activity was associated mostly with the 19S fraction of the immune serum and could be absorbed out with an antigenic fraction of the parasite membrane. Antigenic determinants involved in this HA reaction consisted of, at least, -d-galactosyl or lactosyl residues.     

Permeability of fresh and stored human erythrocytes to glycerol and its acylated derivatives

Summary The effect of copper ions on the permeation of glycerol and its mono-, di-, and triacetate derivatives was studied in fresh and stored erythrocytes. Permeability was unchanged with storage. Acylated glycerols permeate the cells mainly by non-facilitated mechanism, as their transport is almost unaffected by copper ions.Portions of this work were included in the graduate thesis of Dr. Yaeger in partial fulfillment of the requirements for the M. D. degree.Acknowledgement. We thank Mrs Dalia Mazor for expert technical assistance.     

Direct observation of the NAD glycohydrolase reaction in human erythrocytes using NMR spectroscopy

Summary The hydrolysis of NAD by the extracellular membrane-associated enzyme NAD glycohydrolase was shown to be readily followed in concentrated suspensions of human erythrocytes using¹H spin-echo nuclear magnetic resonance spectroscopy (NMR). The maximal rate of the reaction was determined and the inhibitory effect of nicotinamide was confirmed by direct NMR observation. In addition, arginine, ergothioneine and iodoacetate did not influence the reaction rate.³¹P NMR analyses of reaction media from whole cells showed that no extraneous degradation of NAD occurred and the only phosphate-containing product was ADP-ribose.The work was supported by the Australian National Health and Medical Research Council     

The role of 2,3-Diphosphoglyceric acid in the potassium transport of human erythrocytes

Zusammenfassung Der 2,3-Diphosphoglyzerat-Stoffwechsel menschlicher roter Blutkörperchen bedingt die Geschwindigkeit des infolge von ATP-Mangels auftretenden K⁺-Austritts. Der rasche K⁺-Austritt der Erythrocyten kann dann auftreten, wenn die Zellen kein 2,3-Diphosphoglyzerat mehr enthalten.

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The excellent technical assistance of Miss E.Mészáros is gratefully acknowledged.     

Inhibition of glucose transport in human erythrocytes by 2,3-dioxoindole (Isatin)

10 mM isatin (2,3-dioxoindole) inhibited glucose influx into human erythrocytes by over 30%. The inhibition is of the competitive type, where the affinity constant (K_t) was increased from 5.71 (control) to 11.11 mM in the presence of isatin with no change in V_max (130 nmol/min/ml packed cells). The observed inhibition of sugar transport by isatin was not mediated through membrane–SH groups accessible to iodoacetate, iodoacetamide, DTNB, DNP or sodium arsenite. Isatin inhibited sugar transport in the presence of 2 mM harmaline, an alkaloid inhibitor of Na⁺, K⁺–ATP_ase activity. The inhibition was non additive which suggests that these two compounds interact with the same or a similar site on the erythrocyte membrane.     

Electron microscopical evidence of the evolution of corynebacteria-like microorganisms within human erythrocytes

Summary The corynebacteria-like microorganisms evoluting in the haemocultures take origin from electron dense granular bodies carried within the erythrocytes.     

The influence of sodium salicylate on the formation of inorganic phosphate in human and rabbit erythrocytes in vitro

Zusammenfassung Natriumsalizylat in Konzentrationen von 2–20×10^–3 M verursacht einen bemerkenswerten Anstieg an anorganischem Phosphat sowohl in Kaninchen- wie auch in Menschenerythrozyten, die in 0,9% Natriumchlorid oder Tyrode-Locke's Lösung mehrfach gewaschen und suspendiert wurden.

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Work performed during the tenure of a Welsh Hospital Board Research Scholarship.