The affinity of mitochondria for Ca++

Riassunto E' stata studiata l'affinità dei mitocondri di fegato di ratto e di cuore di coniglio per il Ca⁺⁺, nel sistema dipendente da energia. Si sono usati tamponi EGTA-Ca⁺⁺ per mantenere la concentrazione del Ca⁺⁺ costante durante l'esperimento. Si è dimostrato che laK _m apparente per il Ca⁺⁺ non è lontana da 10^–6 M.

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We are indebted to Dr.B. Chance for many stimulating discussions and for facilitating the progress of the work with the generous hospitality in his Institute.     

Ambiguous effect of caffeine upon the transmembrane Ca current in mammalian ventricular myocardium

Zusammenfassung Coffein (20 mM) wirkt auf den transmembranären Ca⁺⁺-Strom der Warmblütermyokardfaser biphasisch. Zunächst nimmt der Ca⁺⁺-Strom zu, was auf einer Verbesserung der Ca⁺⁺-Leifähigkeit des langsamen Membrankanals beruht. Nach längerer Einwirkungsdauer von Coffein kommt es dagegen zu einer Abnahme des Ca⁺⁺-Stroms. Als Ursache hierfür wird vor allem eine Verminderung des transmembranären Konzentrationsgradienten für Ca⁺⁺ — infolge eines Anstiegs der freien Ca⁺⁺-Konzentration im Zellinnern — postuliert.     

Repressible alkaline phosphotase inAspergillus niger

Summary ALP fromA. niger is a) P_i repressible enzyme; b) stimulated by addition of Zn⁺⁺ to the growth medium, and c) that EDTA inhibits the enzyme reversibly, which could be restored by addition of Zn⁺⁺ and perhaps Mg⁺⁺. This property is in contrast to the enzyme fromN. crassa, which is independent of any metal requirement.     

Zur Wirkung von Zn++ auf die Nukleinsäurebiosynthese von Aszites-Tumorzellen

Summary Ascites tumour cells have been employed to study the reactivity of Zn⁺⁺ on nucleic acid biosynthesis. 10^–4 M Zn⁺⁺ caused a selective inhibition of DNA synthesis of intact cells. The rate of RNA- and protein-biosynthesis, however, remained unchanged. The activity of DNA polymerase as well as DNA dependent RNA polymerase was strongly affected by Zn⁺⁺ in vitro.     

Influence of ethanol on calcium,inositol phospholipids and intracellular signalling mechanisms

Summary Studies have implicated Ca⁺⁺ in the actions of ethanol at many biochemical levels. Calcium as a major intracellular messenger in the central nervous system is involved in many processes, including protein phosphorylation enzyme activation and secretion of hormones and neurotransmitters. The control of intracellular calcium, therefore, represents a major step by which neuronal cells regulate their activities. The present review focuses on three primary areas which influence intracellular calcium levels; voltage-dependent Ca⁺⁺ channels, receptor-mediated inositol phospholipid hydrolysis, and Ca⁺⁺/Mg⁺⁺-ATPase, the high affinity membrane Ca⁺⁺ pump.Current research suggests that a subtype of the voltage-dependent Ca⁺⁺ channel, the dihydropyridine-sensitive Ca⁺⁺ channel, is uniquely sensitive to acute and chronic ethanol treatment. Acute exposure inhibits, while chronic ethanol exposure increases⁴⁵Ca⁺⁺-influx and [³H]dihydropyridine receptor binding sites. In addition, acute and chronic exposure to ethanol inhibits, then increases Ca⁺⁺/Mg⁺⁺-ATPase activity in neuronal membranes. Changes in Ca⁺⁺ channel and Ca⁺⁺/Mg⁺⁺-ATPase activity following chronic ethanol may occur as an adaptation process to increase Ca⁺⁺ availability for intracellular processes. Since receptor-dependent inositol phospholipid hydrolysis is enhanced after chronic ethanol treatment, subsequent activation of protein kinase-C may also be involved in the adaptation process and may indicate increased coupling for receptor-dependent changes in Ca⁺⁺/Mg⁺⁺-ATPase activity.The increased sensitivity of three Ca⁺⁺-dependent processes suggest that adaptation to chronic ethanol exposure may involve coupling of one or more of these processes to receptor-mediated events.     

Komplex-Stabilität und tuberkulostatische Aktivität einiger 8-Oxychinolinderivate

Summary Based on polarographic viz. spectrophotometric determinations of the stabilities of several Cu⁺⁺- and Co⁺⁺⁺ hydroxyquinolin complexes it has been shown that a correlation exists between the quotient of complex-stabilitiesK _Co ⁺⁺⁺ /K _Cu ⁺⁺ and antitubercular activity (cf. table and graph). This supports the hypothesis that the 8-hydroxyquinolin derivatives and analogues act by competitive antagonism; the Cu⁺⁺-hydroxy-quinolates are able to replace Co in a prosthetic group of Mycobacterium-enzyme with Cu.

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Vorgetragen an der Organisch-Chemischen Konferenz des Vereines ungarischer Chemiker, 27. September 1953.

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III. Mitteilung: Acta chim. Hungarica (im Druck).     

The effects of the ‘calcium-antagonist’, prenylamine,on the action potential of crayfish muscle (Oronectes virilis)

Zusammenfassung Der organische Ca⁺⁺-Antagonist Prenylamin blockiert die leicht reversiblen Ca⁺⁺-Aktions-potentiale in der Muskelfaser des FlusskrebsesOronectes virilis. Etwas niedrigere Konzentrationen erhöhen die Schwelle und verlängern die Dauer, während schwache Konzentrationen von Prenylamin nur wirksam waren, wenn dieses verwendet wurde, bevor der Muskel dem Aktionspotentialerreger Procain oder Sr⁺⁺ ausgesetzt war.     

Studies of total and protein-bound plasma Mg++ in wild and hatchery-reared coho salmon smolts in freshwater and in seawater

Summary Total plasma Mg⁺⁺ and Ca⁺⁺, Mg⁺⁺ in erythrocytes as well as protein-bound plasma Mg⁺⁺ were investigated in wild and hatchery-reared smolts. The proportion of plasma Mg⁺⁺ which was bound to plasma protein did not change significantly during entry into seawater, even though the in vitro addition of exogenous Mg⁺⁺ to the plasma showed that additional binding was possible.     

Phosphoproteinphosphatase activity in sea urchin embryos

Riassunto Si è studiata l'attività fosfoproteinfosfatasica in omogenati totali di uova ed embrioni diParacentrotus lividus e diArbacia lixula. La reazione ha un optimum a pH acido, è stimolata da K⁺ e Na⁺ ed è inibita da Ca⁺⁺ e Mg⁺⁺. L'attività enzimatica aumenta tra la fecondazione e lo stadio a 64 blastomeri; in seguito rimane costante fino a blastula con mesenchima; quindi generalmente decresce.

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This work has been supported by a grant from the Consiglio Nazionale delle Ricerche to the Laboratory of Comparative Anatomy (Research Group of Embryology).     

Variations de l'activité des auxines-oxydases dans les racines duLens

Summary 2, 4-dichlorophenol (DCP), 2, 4-dinitrophenol (DNP) and 2, 4-dinitro-o-cresol (DNC) applied at a concentration of 1.10^–7 to 1.10^–3 M, produce a dramatic increase in IAA-oxidase activity in young cells ofLens root. IAA destruction by breis from root tissues was inhibited by Mn⁺⁺ ion at low concentrations of DCP (1·10^– to 1.10^–7 M), but was enhanced by Mn⁺⁺ ion at higher (1.10^–5 to 1.10^–3 M) DCP levels.

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Ce travail a pu être entreprise grâce à l'appui duFonds national suisse pour la Recherche scientifique.     

Possible role of intestinal alkaline phosphatase activity in thiamine transport

Summary Thiamine deficiency caused a marked decrease of intestinal alkaline phosphatase (al-Pase) activity, but had no effect on the Ca⁺⁺-ATPase activity and Ca⁺⁺-absorption in rats. The al-Pase activity was significantly decreased 1 h after oral administration of ethanol at 0.5 and 2.5 g/kg. In contrast, Mg⁺⁺-, Ca⁺⁺- and (Na⁺+K⁺)-ATPase activities did not change after the administration of ethanol. These findings show that the al-Pase activity, unlike the Ca⁺⁺-ATPase activity, is not related to Ca⁺⁺-absorption. A possible role of al-Pase activity in the active transport of thiamine in the intestine was discussed.     

Influence de la vagotomie chez la tancheTinea tinca au cours d'une surcharge pluricationique (eau de mer diluée). Variation des cations Na+, K+, Ca++ et de l'intensité de la respiration tissulaire

Summary Respiratory ionic content (Na⁺, K⁺, Ca⁺⁺) of hepatic tissue and ionic excretion measurements were performed in the TenchTinea tinea kept in diluted sea water. After bilateral section of parasympathetic system, the changes of Na/K value are less than in fresh water. The survival and hepatic O₂ uptake were the same. It is suggested than after both vagi section sea water Ca⁺⁺ allowed a best osmoregulation in this species.

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Ce travail a été réalisé avec la collaboration technique de A.Rup.     

Polyacrylamide gel disc electrophoresis of rat bile after intravenous administration of52MnCl2,64CuCl2,203HgCl2, and210Pb(NO3)2

Résumé Après avoir administré i. v. à des rats les solutions des sels Pb⁺⁺, Hg⁺⁺, Mn⁺⁺ et Cu⁺⁺, on a divisé leur bile par des l'élécrophorèse de disque sur gel de polyacrylamide. Les cations Hg⁺⁺ se sont montrés surtout dans la fraction contenant des hauts polymères d'albumine spécifique pour la bile; les cations Mn⁺⁺ et Cu⁺⁺ furent observés surtout dans la zone pigmentée. Le maximum des cations Pb⁺⁺ attachés s'est trouvé dans la zone de postalbumine.     

Die Abhängigkeit der Ca++-Aufnahme isolierter Mitochondrien des Herzmuskels von der Na+-und K+-Konzentration als mögliche Ursache der inotropen Digitaliswirkung

Summary In isolated mitochondria of heart muscle from rabbits and oxen there is, under suitable conditions, an accumulation of Ca⁺⁺, which is significantly enhanced by elevating the K⁺/Na⁺ quotient of the incubation medium. K-strophanthine (10^–5–10^–7) does not influence the accumulation of Ca⁺⁺ by the mitochondria of heart muscle. Therefore the intracellular increase in exchangeable Ca⁺⁺ observed after digitalis-glycosides could be explained by a decrease of the intracellular K⁺/Na⁺ quotient, which is caused by inhibition of the membrane ATPase and diminishes the capacity for Ca⁺⁺ accumulation in mitochondria.     

Phosphorylation of cockroach antennal polypeptides: effects of second messengers and pheromonal blend

In insect antennal extracts, Schleicher et al.¹ showed that protein kinase C (PKC) inhibitors abolish the transience of pheromone-induced rapid inositol trisphosphate responses, which suggests that pheromonal signals act on phosphorylation of specific proteins. To confirm this hypothesis, we studied the effects of second messengers and a pheromonal blend on phosphorylation of antennal proteins in the cockroachPeriplaneta americana. Proteins from adult male antennae were phosphorylated in vitro in the presence of [³²P] triphosphate, then separated by SDS-polyacrylamide gel electrophoresis. Numerous phosphopolypeptides were visualized. The presence of Ca⁺⁺/calmodulin in the incubation medium resulted in increased phosphorylation of polypeptides with molecular weights of 38, 48, 51, 54 and 58 kDa. Stimulation of PKC by addition of Ca⁺⁺ phosphatidylserine (PS)/phorbol myristate acetate (PMA) resulted in the appearance of three phosphopolypeptides of 36, 70 and 120 kDa. In the presence of cyclic adenosine monophosphate, two new major polypeptides of 46 and 42 kDa appeared; the latter polypeptide also appeared in the presence of cyclic guanosine monophosphate. Comparison with polypeptide composition of tissue from the cerci, leg, brain and fat body showed that the 36 and 48 kDa polypeptides were specific to antennae, whereas the 120 kDa polypeptide was also present in the adult brain. When antennae are subjected to pheromonal stimulation for 16 seconds prior to homogenization, in vitro phosphorylation of the 120, 70, 64 and 38 kDa polypeptides was inhibited, whereas phosphorylation of the 58, 54, 51 and 48 kDa polypeptides was strongly stimulated. It is noteworthy that a 107 kDa polypeptide was observed only after pheromonal stimulation by Ca⁺⁺/PS/PMA. Our findings suggest that Ca⁺⁺-and PKC-dependent protein phosphorylation systems play an important role in the transduction of pheromonal signals in antennae of male cockroachP. americana. We speculate that specific phosphoproteins may modulate sensitivity and signal amplification during the olfactory transduction process.     

Magnesium enhances human pancreatic elastase digestion of125I-labeled elastin

Summary The effect of some divalent cations, especially Mg⁺⁺, on elastinolysis by porcine or human pancreatic elastase has been determined using¹²⁵Iodine-labeled elastin as substrate. Elastin degradation was significantly increased in the presence of 10^–3 M Mg⁺⁺. If elastin was pre-incubated with 0.5 (w/v) Triton, there was a further increase in elastinolysis to 2.6 times the original rate.     

Untersuchungen über den Einfluss verschiedener Kationen auf die ATP-Spaltung durch die Zytoplasmafraktion vom Plexus chorioideus des Rindes

Summary The cytoplasma fraction of the bovine choroid plexus epithelial cells was found to contain a considerable ATPase activity. The influence of Na⁺, K⁺, Li⁺, Rb⁺, Cs⁺, Co⁺⁺, Mn⁺⁺, Zn⁺⁺ and Fe⁺⁺⁺ on the activity of the Mg⁺⁺-dependent enzyme has been studied. The monovalent cations do not influence the enzymic activity, whereas the effect of the bi- and trivalent cations is characterized by an inhibition of the ATPase.     

Inhibition of riboflavin-sensitized photoinactivation of taka-amylase a by some inhibitors

Zusammenfassung Durch Gegenwart von Co⁺⁺ oder J^– oder Tryptophan oderp-Phenylendiamin wird die durch Riboflavin sensibilisierte Photoinaktivierung der Taka-Amylase A stark gehemmt. Die möglichen Mechanismen der Hemmungswirkung dieser Inhibitoren werden diskutiert.     

Enzymatic phosphorylation of proteins of rat liver chromatin by (γ-32P) ATP in vitro

Zusammenfassung Isoliertes Rattenleberchromatin baut die endständige Phosphat-Gruppe von (-³²P) ATP in seine Proteine in Form von Phosphatester von Serin und Threonin ein. Der Einbau ist Mg⁺⁺ und Mn⁺⁺ abhängig und steigt mit Erhöhung des pH des Inkubationsmediums an. Phosphat und Pyrophosphat stimulieren die Phosphorylierung, zyklisches AMP hat keinen Effekt. Die sauren Proteine werden viel stärker als die Histone phosphoryliert. Das eingebaute Phosphat wird sehr schnell freigesetzt, ein Prozess, der von der Anwesenheit von dephosphorylierenden Enzymen abhängt.