Versuche zur Charakterisierung einer Transport-ATPase f�r Na+ und K+ in der Zellmembran des Herzmuskels

Portius, H. J.; Repke, K.

doi:10.1007/bf00260049

Cited by 11 publications

(3 citation statements)

References 9 publications

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“…Judah & Ahmed (1962, 1964 suggested that the two ions were antagonistic in a reaction involving the turnover of phosphoprotein in liver slices. More directly relevant, Portius & Repke (1962) reported that inhibition by Ca2+ of the Na+-plus-K+-activated ATPase of heart muscle was reversed by raising the Na+ concentration. Our results with kidney cortex, however, show that the inhibition by calcium was unaffected by a large change in the concentration of Na+ of the medium.…”

Section: Discussionmentioning

confidence: 99%

The mode of inhibition by calcium of cell-membrane adenosine-triphosphatase activity

Fh¹,

Whittam²

1966

Biochemical Journal

139

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1. The mechanism of the inhibition of Na(+)-plus-K(+)-activated adenosine triphosphatase by calcium was investigated with an enzyme preparation from rabbit kidney cortex and with membranes of human erythrocytes. 2. CaATP, rather than ionic Ca(2+), acts as a competitive inhibitor, competing with MgATP in the Na(+)-plus-K(+)-activated adenosine-triphosphatase reaction. 3. There appears to be no competition between calcium and Na(+) for the activation of adenosine triphosphatase. 4. The inhibition of Na(+)-plus-K(+)-activated adenosine triphosphatase of cell membranes by low concentrations of CaATP and the consequent need of intact cells to keep the cytoplasmic concentration of calcium low relative to that of magnesium suggests a raison d'être for the mitochondrial calcium pump.

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Section: Discussionmentioning

confidence: 99%

The mode of inhibition by calcium of cell-membrane adenosine-triphosphatase activity

Fh¹,

Whittam²

1966

Biochemical Journal

139

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“…The presence of androstane-3a-, and -3j8-hydroxysteroid dehydrogenases which transform androstanedione to androsterone and epiandrosterone, respectively, was reported in rat liver homogenate (21), and the reverse reaction, from androsterone to 5a-androstanedione, was observed in rabbit liver slices (22) and bovine erythrocyte suspensions (23).…”

Section: Discussionmentioning

confidence: 93%

Bioconversion of Steroids in Immature Rat Testesin Vitro1

Itoh¹,

Tamaoki²

1966

Endocrinology

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Among the testicular enzymes related to steroid bioconversion, the A B -3/3-hydroxysteroid dehydrogenase, together with the isomerase, and the 17/3-hydroxysteroid dehydrogenase activities per testis were found to be low in the testicular microsomes of immature rats (27-day-old), in comparison with those of adult rats (90-day-old), while the 17«-hydroxylase and the pregnene-Ci7-Coo lyase activities were found to be relatively active in immature rat testes. After incubation of 17 a-hydroxy progesterone and androst-4-ene-3,17-dione separately with the testicular microsomes of immature rats, 3«, 17«-dihydroxy-5«-pregnan-20-one was obtained as one of the major metabolites of 17a-hydroxyprogesterone, and 5a-androstane-3,17-dione, 3«-hydroxy-5a-androstan-17-one, and 3/3-hydroxy-5«-androstan-17-one as metabolites of both substrates. The enzymic pattern unique to the testes of immature rats would seem to be the significantly strong activities of the A 4 -androstene and -pregnene-5a-reductase, the 5a-androstane-3«-,

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“…In the technical model, the battery is situated in the electronic branch of a closed circuit. In the VINMC, the pumps (generators) are situated in the membranes of the circuit as, e.g., N a + K + -ATPase enzymes (35)(36)(37)(38)(39)(40)(41)(42). In both instances they are electrically able to produce an electrical potential gradient.…”

Section: Phase Of Charging the Neuronmentioning

confidence: 99%

VI. Synaptic Fuel Cell Reactions in Vascular-Interstitial-Neuromuscular Closed Circuit: Theory of Neuromuscular Activation

Nordenström

1993

Electro- and Magnetobiology

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Spontaneous pulses of voltage occur in the caval vein at voluntary contraction of a leg muscle both in the rat and in humans. Morphology and vascular reactions indicate that vascular-interstitial-neuromuscular circuits (VINMC) exist. They require redox reactions, which are likely to occur at proteins in the cellular membranes of the synapse. Metabolic degradation of ATP in the nerve cell is known to generate a flow of current out of the cell, creating the resting potential. It corresponds to an electrochemical equilibrium potential. An overpotential leads to a closed circuit flow of current in the VINMC, producing redox products at the electrode equivalent redox proteins. The VINMC is thereby charged. Brain impulses open ionic channels of the nerve cell body, short-circuiting the VINMC. Electrochemical reactions by the redox products produce an action potential and reverse the current in the charged VINMC. The charging and discharging of the synaptic membranes are explained as electrochemical analogs. The action potential and its height, production, transport, and disappearance of various synaptic products, including vesicles and the voltage pulses in the associated vessels such as the caval vein and the aorta, can be explained. 99

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Versuche zur Charakterisierung einer Transport-ATPase f�r Na+ und K+ in der Zellmembran des Herzmuskels

Cited by 11 publications

References 9 publications

The mode of inhibition by calcium of cell-membrane adenosine-triphosphatase activity

The mode of inhibition by calcium of cell-membrane adenosine-triphosphatase activity

Bioconversion of Steroids in Immature Rat Testesin Vitro1

VI. Synaptic Fuel Cell Reactions in Vascular-Interstitial-Neuromuscular Closed Circuit: Theory of Neuromuscular Activation

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