Insulin effect in vitro on human erythrocyte plasma membrane

Summary The effect of porcine insulin has been tested in vitro on human erythrocyte plasma membrane (Na⁺–K⁺) and Mg²⁺-ATPase activities as well as on membrane fluidity. The results indicate that the hormonal treatment significantly inhibits (Na⁺–K⁺)-ATPase activity, and at the same time decreases membrane fluidity.This investigation has been supported by Consiglio Nazionale delle Richerche, Rome, Italy.     

Effect of free fatty acids and cholesterol in vitro on liver plasma membrane-bound enzymes

Summary The effect of cholesterol and fatty acid treatment in vitro was tested on rat liver plasma membrane-bound enzymes and lipid fluidity. The observed alterations of membrane fluidity affect both (Na⁺–K⁺)-ATPase and Mg²⁺-ATPase activities but not 5-nucleotidase; basal adenylate cyclase as well as its hormonal sensitivity were differentially affected by changes of membrane microenvironment.This investigation was partially supported by the Italian National Research Council.     

Effect of heat treatment on the ATPase activity of various sarcoplasmic reticulum preparations

Summary Ca²⁺-stimulated ATPase activity of sarcoplasmic reticulum (SR) preparations is activated after a short period of preincubation at temperatures between 40 and 45°C, but for temperatures higher than 48°C pronounced denaturation is observed. Heat denaturation is decreased if Mg²⁺ or K⁺ are present during heat treatment.Acknowledgments. This work was supported by research grants from Instituto de Alta Cultura (Grant No. CB/2) and the Calouste Gulbenkian Foundation. We are grateful to Drs.A. P. Carvalho andV. M. C. Madeira for many discussions and suggestions during the course of this work.     

Demonstration of a negative binding effect of bovine growth hormone toward potassium

Zusammenfassung Hochgereinigtes Rinderwachstumshormon besitzt ein ziemlich gutes Bindungsvermögen für Mg⁺⁺-, Ca⁺⁺- und Na⁺-Ionen. Andererseits wird K⁺ je nach Konzentration überhaupt nicht, oder nur in Spuren gebunden.

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The performance of the elementary analyses by R. C.Anderson is gratefully acknowledged. Thanks are also due to B.Czuk and N. O.Milkovich for technical assistance.     

Distribution of tritium inWilzbach treated cholesterol

Zusammenfassung Es wird gezeigt, dass Cholesterin-H³, nach Behandlung von besonders gereinigtem Handelscholesterin mit Tritium entsprechend der Vorschrift vonWilzbach, bei sechsmal wiederholter Bromierung nachFieser frei von Cholestanol-H³ erhalten wird. In so gereinigtem Cholesterin-H³ ist der schwere Wasserstoff gleichmässig über alle wasserstofftragenden Kohlenstoffatome verteilt.

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This work was supported by an Institutional Grant No. P-108A of the American Cancer Society and by a Grant No. G-7477 of the National Science Foundation. The authors are grateful to Dr.M. Gut of this Institute for theWilzbach treatment of cholesterol.     

Dissociation between compensatory renal growth and induction of (Na++K+-ATPase in rat kidney after uninefrectomy

Zusammenfassung Nach Uninephrektomie und bilateraler Adrenalektomie entsteht eine Dissoziation zwischen der Nierenvergrösserung und der (Na⁺+K⁺)-ATPase Aktivität. Es besteht wahrscheinlich kein Zusammenhang zwischen der Nierenvergrösserung und der Induktion von (Na⁺+K⁺)-ATPase. Auch in der vergrösserten Niere sind die Nebennierenhormone notwendig, um die (Na⁺+K⁺)-ATPase zu erhalten.

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The work was supported by a grant from P. Carl Petersen's Fund. Mrs.Birthe Bagge Hansen provided excellent technical assistance.     

Effect of potassium and norepinephrine on the tone of the isolated artery: Changes by ouabain pretreatment

Zusammenfassung Vorbehandlung von Arterienstreifen mit g-Strophantin (>10^–8 g/ml) kehrt die mechanische Reaktion auf K⁺-Änderungen im Bereich von 1 bis 10 mM KCl, nicht aber die K⁺-Wirkung auf die Kontraktion durch Noradrenalin oder Barium um. Danach könnte die K⁺-Dilatation der Arterien auf der Aktivierung einer elektrogenen Na⁺-Pumpe beruhen.

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The authors gratefully acknowledge the technical assistance by Mrs.B. Heinemann.     

The Ca2+-transport ATPases in smooth muscle

Summary A calmodulin stimulated Ca²⁺-transport ATPase which has many of the characteristics of the erythrocyte type Ca²⁺-transport ATPase has been purified from smooth muscle. In particular, the effect of calmodulin on these transport enzymes is mimiced by partial proteolysis and antibodies against erythrocyte Ca²⁺-transport ATPase also bind to the smooth muscle (Ca²⁺+Mg²⁺)ATPase. A correlation between the distribution of the calmodulin stimulated (Ca²⁺+Mg²⁺)ATPase and (Na⁺+K⁺)ATPase activities in smooth muscle membranes separated by density gradient centrifugation suggests a plasmalemmal distribution of this (Ca²⁺+Mg²⁺)ATPase. A phosphoprotein intermediate in smooth muscle which strongly resembles the corresponding phosphoprotein in sarcoplasmic reticulum of skeletal muscle may indicate the presence in smooth muscle of a similar type of Ca²⁺-transport ATPase.     

Intestinal uptake of ouabain and digitoxin in the milkweed bug,Oncopeltus fasciatus

Summary The absorption of ouabain and digitoxin into the gut of the milkweed bug was studied by a tissue-accumulation technique. Uptake of both compounds obeyed diffusion kinetics, was Na⁺ sensitive, and for digitoxin, was concentrative.The authors express their appreciation to Dr.James A. Slater and Ms.Flavia O'Rourke, Biological Sciences Group, University of Connecticut, Storrs, Conn. (USA) for supplying milkweed bugs. This work was supported by the University of Maine Honors Program and the University of Maine Agricultural Experiment Station.     

Die Wirkung von Makrotetralidantibiotika auf photosynthetische Reaktionen in Spinatchloroplasten

Summary The macrotetralid antibiotic Dinactin uncouples phosphorylation from electron transport in illuminated chloroplasts in the presence of Na⁺ at lower concentrations than in K⁺, while the light-induced proton uptake is more inhibited in a medium with K⁺ than with Na⁺. The large volume changes of whole chloroplasts in the light and after addition of Dinactin are parallel to the amount of K⁺ in the chloroplasts.

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Die Resultate der vorliegenden Arbeit entstanden zusammen mitElisabeth Bosshard-Heer, H. R. Hohl, Ch. Pflugshaupt undIngrid Specht-Jürgensen. Wir danken dem Schweizerischen Nationalfonds für die grosszügige Unterstützung.     

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.     

Effect of cholesterol oxidation on (Na+, K+) ATPase activity of erythrocyte membranes.

By incubation of human erythrocyte ghosts with cholesterol oxidase (EC 1.1.3.6) part of the cholesterol of the membrane is replaced by 4-cholesten-3-one. This alteration in the sterol composition is accompanied by an inhibition of the (Na+, K+) ATPase of the erythrocyte membrane.     

Membrane potentials of the squid giant axon recorded with an inserted antimony microelectrode

Résumé Les enregistrements pris simultanément des axones géants deLoligo au moyen de microélectrodes de KCl et de l'antimoine donnent à peu près les mêmes valeurs pour le potentiel de repos et pour la pointe. Les deux microélectrodes enregistrent d'une façon identique les changements de potentiel de la membrane pendant la dépolarisation avec KCl et pendant la restitution. Bien que les microélectrodes de Sb restent toujours réversibles à H⁺, les potentiels enregistrés ne correspondent pas à la distribution de H⁺. Ces données, comme d'autres, indiquent que le potentiel de repos n'est pas une conséquence des distributions deDonnan, mais plutôt, selon toute probabilité, un effet des propriétés de la membrane électrogène.

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This work was carried out at the Marine Biological Laboratory, Woods Hole, Mass., with a grant under MBL contract (Nonr-09705). Additional aid was received from American Philosophical Society, Muscular Dystrophy Associations of America, National Science Foundation and United Cerebral Palsy Associations.     

Patterns of membrane organization in toad bladder epithelium: A freeze-fracture study

Summary Two cell-types of toad bladder epithelium show uncommon plasma membrane organization in freeze-fractured specimens. One type, the granular cell, contains a plasma membrane in which the A-face is poorly particulate luminally while the B-face discloses multiple large particles at this site. In contrast, the lateral and basal portions of the granular-cell membrane are typical in that more particles occupy the A-face than the B-face. In the other cell-type, which is mitochondriarich, the plasma membrane, luminally, laterally, and basally, contains rod-shaped and a few glubular particles in the A-face. We suggest that these two peculiar membrane organizations by considered in the localization of both vasopressin and aldosterone action in toad bladder.Some of these results were presented in abstract form at the 6th annual meeting of the Swiss Societies for Experimental Biology, Lausanne, 11–12, May 1974²¹ The authors are indebted to Mrs.Marthe Sidler-Ansermet, Mrs.Gorana Perrelet, MissMariella Ravazzola and Mr.Michel Bernard for valuable assistance.This work was supported in part by grants No. 3.0311.73, 3.8081.72, 3.553.75 and 3.1300.73 from Fonds National Suisse de la Recherche Scientifique, Bern, Switzerland, and by a grant-in-aid from Hoechst-Pharmaceuticals (Frankfurt-Hoechst, W. Germany).     

Affinity chromatographic preparation of arterial heavy meromyosin subfragment-1

Summary Heavy meromyosin subfragment-1 (HMM S-1) was prepared by papain digestion of arterial myosin or actomyosin and was purified by agarose-ATP affinity chromatography. Proteolysis of crude arterial myosin suspensions was preceded by solubilization. HMM-S-1 thus obtained consisted mainly of a 90,000 dalton polypeptide and fully retained the K⁺- and Ca²⁺-ATPase of the parent myosin. Its affinity to agarose-ATP was comparable to that of skeletal muscle HMM S-1.The support of this work by an EMBO short time fellowship (to R. L.) and by the Deutsche Forschungsgemeinschaft (No. SFB 90, B 7) and the excellent technical assistance byM. Troschka andC. Köhler are gratefully acknowledged.     

Effects of Mn2+ and Mg2+ on the pigeon liver pyruvate kinase

Riassunto Mn²⁺ and Mg²⁺ attivano la piruvato cinasi di fegato di piccione in maniera distinta. In presenza di basse concentrationi di fosfoenolpiruvato Mn⁺ é piú efficace di Mg²⁺ ed é attivatore dell'enzima saturato da Mg²⁺. Piruvato cinasi (EC 2.7.1.40).

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This work was supported by a grant from the Consiglio Nazionale delle Ricerche, Roma, Italia.Silvia Baldi is a fellow of the Italian C.N.R.     

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.     

Behaviour of sodium-potassium-activated adenosine triphosphatase in rat kidney tissue by folic acid

Zusammenfassung Männliche Wistarratten zeigten nach i.v. Gabe von Folsäure einen Aktivitätsabfall der Enzyme, die in den aktiven Ionentransport eingreifen: (Na⁺K⁺) ATPase (60% gegenüber Kontrollen), ICDH (56%) und MDH (48%) und a.Ptase (66%).

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With technical assistance of Mrs. I.Bieder and Miss M.Kirstein.

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With the support of the Schweiz. Nationalfonds zur Förderung der wissenschaftlichen Forschung No. 4809.     

Aging of the erythrocyte. III. Cation content

Summary Studies on the main cation content of density-separated bovine erythrocytes showed a progressive decrease in the levels of K⁺ and Mg²⁺ with increasing cell density (and age) accompanied by an increase in the level of Na⁺. The magnitude of net cation loss corresponded to that of red cell volume decrease, but could not account for the total increase in the microviscosity of the erythrocyte interior.     

Die Reversibilität der Wirkung von Digitoxin,Strophanthidin und Strophanthidin-3-bromazetat am Papillarmuskel und einer mikrosomalen Na+-K+-aktivierbaren ATPase des Meerschweinchens

Summary The reversibility of the inhibitory action of strophanthidin, strophanthidin-3-bromoacetate, and digitoxin on the Na⁺-K⁺-ATPase activity (microsomal fraction, guinea-pig brain) was compared with the rate of decline of their positive inotropic effects (papillary muscle, guinea-pig heart) after exposure to drug-free solution. The actions of strophanthidin and digitoxin were easily reduced on both systems. Strophanthidin-3-bromoacetate, however, was found to have an irreversible blocking effect on the transport ATPase, whereas its inotropic action could be rapidly abolished.

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Teilergebnisse der Dissertation von U.Fricke, Mainz.