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Results for “Calcium-Transporting ATPases”

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At least 253 records · Page 14Linked to original sources
PubMed1979

Diamide inhibited (Ca++ + Mg++) and (Mg++) dependent ATPase in erythrocyte membranes: activity at different temperatures.

After inhibition of the monovalent cation dependent ATPase, a (Ca++ + Mg++) and a (Mg++) dependent ATPase activity can be detected. The inhibition due to diamide on the (Mg++) ATPase, assayed in the 12.5 degrees C - 30 degrees C temperature range, is almost complete. On the contrary the diamide induced inhibition of (Ca++ + Mg++) ATPase, in the same temperature range, is not complete and the residual activity increases with temperature. The reported data indicate that the ATPase activity induced by calcium is much less diamide-sensitive and -SH-dependent than that elicited by Mg++ alone.

Adenosine Triphosphatases↗
PubMed1979

[Effect of thermostable protein kinase modulator on Mg, Ca-ATPase from nervous tissue].

Isoelectric focusing of a purified fraction of thermostable modulator of 3',5'-AMP-dependent protein kinase revealed five individual proteins, the main protein having an isoelectric point of 4,05. The molecular weight of this protein as determined by gel filtration is 8000--9000. The protein with a pI of 4,05 binds Ca2+ and in contrast to the original modulator inhibits the endogenous 3',5'-AMP-dependent phosphorylation of synaptic membranes. An addition of the original modulator fraction to the microsomes isolated from nervous tissue increases the Mg, Ca-ATPase activity and absorption of 45Ca. Neither the protein with a pI of 4,05 nor other individual proteins affect the activity of transport ATPase. The activating effect is partly restored after mixing of all the five subfractions. It is assumed that these proteins are aggregated by Ca2+ and change the activity of ATPase or membrane 3',5'-AMP-dependent protein kinase depending on the concentration of calcium ions.

Animals↗
PubMedDate not supplied

[Participation of Mg2+ and Ca2+ ions and the corresponding ATPases in the mechanism of the presynaptic action of amisyl and arecoline].

Amisyle and arecoline were found to be antagonistic drugs in the effect on content of Mg2+ and Ca2+ and on activity of corresponding ATPases in synaptosomes isolated from rat brain. Amisyle promoted the incorporation of 45Ca into synaptosomes but arecoline inhibited the reaction. The appear to be responsible for liberation and maintaining of neurotransmitters in presinaptic stores.

Adenosine Triphosphatases↗
PubMed1979

Subcellular calcium localization and AT0-dependent Ca2+-uptake by smooth endoplasmic reticulum in an invertebrate photoreceptor cell. An ultrastrucutral, cytochemical and X-ray microanalytical study.

In Hirudo medicinalis an extensive and highly elaborate three dimensional network of smooth endoplasmic reticulum cisternae is found in very close structural relationship to the receptive (microvillar) membrane, as reported for many other invertebrates. A variant of the potassium pyroantimonate technique showed that these submicrovillar endoplasmic reticulum cisternae (SMC) and mitochondria are major intracellular calcium stores. Furthermore, using saponine-skinned photoreceptors for an in situ accumulation experiment, calcium oxalate precipitates in SMC demonstrate that this organelle is able to accumulate Ca2+ from a concentration of 2 x 10(-5) M, when ATP, Mg2+, and oxalate ions are present in the accumulation medium. This result provides direct evidence for the hypothesis that SMC may play a particularly important role in the regulation of intracellular ionized calcium in invertebrate photoreceptor cells. Morphological evidence supports this view.

Animals↗
PubMed1975

Histoenzymatic changes in the dog kidney in an experimentally induced crushing injury of the thorax.

The experiments were carried out on dogs. Experimental animals were subjected to the trauma of the thorax during operation. The localization and activity of succinic dehydrogenase, NADH2-tetrazole reductase, adenosine triphosphatase, alkaline and acid phosphates in the kidneys were examined. An increase of the activity of all the investigated enzymes takes place under the influence of the stress. On the basis of the investigations it can be supposed that the processes of oxygen phosphorylation and active transport are intensified. An increase of the activity of acid phosphates gives evidence of the intensity of phagocytosis and pinocytosis processes in the kidney.

Acid Phosphatase↗
PubMed1979

Calcium handling by cardiac sarcoplasmic reticulum.

Over the past ten years knowledge of the biochemistry of cardiac sarcoplasmic reticulum vesicles has been considerably extended. In almost all respects the Ca2+ pump of cardiac sarcoplasmic reticulum shows striking similarities to the Ca2+ pump of skeletal muscle sarcoplasmic reticulum. On the other hand, Ca2+ release mechanisms seem to be more complex in cardiac than in skeletal sarcoplasmic reticulum. Future research undoubtedly will involve characterizing the function of the many additional proteins present in cardiac sarcoplasmic reticulum, and determining possible roles for these proteins in regulating Ca2+ uptake and Ca2+ release by these membranes.

Animals↗
PubMed1977

Ca2+-activated ATPase of rat liver plasma membrane.

Rat liver plasma membranes hydrolyze ATP in the presence of Ca2+. The rate of hydrolysis is different when Mg2+ions are present in the incubation system. Several parameters differentiate Ca2+-ATPase from Mg2+-ATPase: a) the Km of ATP hydrolysis for Ca2+ (2.25 x 10(-4) M) is lower than for Mg2+ (2.14 x 10(-3) M); b) the shape of the activation curve is hyperbolic in the presence of Ca2+ and sigmoid in the presence of Mg2+; c) Mg2+-ATPase shows two different values of activation energy while Ca2+-ATPase presents only a single value; d) Ca2+-ATPase is inhibited, while Mg2+-ATPase is unaffected by cyclic AMP. Ca2+-ATPase is localized on the plasma membrane and is not inhibited by cysteine. It does not hydrolyze substrates different from nucleotides triphosphate, such as glucose-1-phosphate or alpha-glycero-phosphate. The enzyme is probably related to a mechanism of calcium transport.

Adenosine Triphosphate↗
PubMed1977

Studies on adenosine triphosphatase activity of rat cardiac myosin in isoproterenol-induced cardiac hypertrophy.

Ca2+- and K+ -activated ATPase activity of cardiac myosin from normal and hypertrophied rat hearts was investigated. Cardiac hypertrophy was induced by isoproterenol treatment. A nearly 40% increase in heart mass was seen after seven consecutive days of isoproterenol injection (5 mg/kg) as determined by either heart weight expressed as per cent of body weight or by dry heart weight and total protein content. The measurement of ATP hydrolysis revealed that cardiac myosin from isoproterenol-treated rats had a significant decrease (P less than 0.01) in Ca2+-activated ATPase activity at low ionic strength (0.05 M KCl) in the presence of 5 and 10 mM Ca2+. In contrast, in a high ionic strength medium (0.50 M KCl) the K+- and Ca2+-activated ATPase activity of myosin prepared from hypertrophied myocardium remained unchanged. Comparative analysis of protein present in the light chains of myosin showed no alteration in the proportion of LC1 to LC2 in the myosin from hypertrophied hearts, however, a decrease in the absorption of myosin in the u.v. region was observed. On the basis of our results one can hypothesize that there may be some conformational change in the myosin molecule from hypertrophied myocardium, thereby modifying both Ca2+-sensitivity and ATPase activity at a low KCl concentration.

Animals↗
PubMed1979

[Biochemical mechanisms for the effect of alcohol on the brain].

This paper reviews and discusses basic knowledge of biochemical mechanisms of action of ethanol upon the central nervous system, the emphasis being on effects upon cerebral membrane structures and processes as well as mechanisms of chemical synaptic transmission. Results of detailed studies into material and steric changes in membranes, ion-dependent adenosine triphosphatases, variations in ion balance, effects upon cyclic nucleotides, influences on special transmitter systems, and mechanisms of formation of morphine-analogous condensation products are presented. In addition, open questions are derived and formulated in problem complexes.

Acetaldehyde↗
PubMed1979

[Studies of the presence of enzymes in various tissues of swine. 5. Studies of the activity and properties of adenosine triphosphatases in the pancreas].

Studies were conducted into the activities of magnesium-ATPase, sodium-potassium-ATPase, and HCO3-ATPase in homogenates of pancreas of 19 foetuses, with body weights between 340 g and 1,642 g, two piglets, with body weights of 9 kg and 10 kg, and four adult pigs. While general enzyme activity was low during foetal development, highest activies usually were recordable from HCO3-ATPase. High activities were recorded from both the piglets and adult pigs. The highest data, again, were recordable from HCO3-ATPase which is essential to the secretion of HCO3 ions. Maximum activity of magnesium-ATPase was based on an ATP-magnesium ratio of 1:1. HCO3-ATPase was best activated by 25 mM NaHCO3 and exhibited high stability to temperature. The activities of magnesium-ATPase and of HCO3-ATPase were inhibited by 10 mM of Rhodanid. Calcium-ATPase reached its maximum activity in response to 5 mM calcium concentration.

Adenosine Triphosphatases↗
PubMed1979

[Role of calcium in realization of nervous control during RNA synthesis in skeletal muscles].

The effects of Ca2+ on the RNA polymerase activity of the nuclei isolated from normal and denervated gastrocnemius muscles of the rabbit were studied. It was shown that 18 hrs after denervation the RNA synthesis in vitro, Ca2+ content and the Ca, Mg-ATPase activity of the nuclei are decreased. After addition of exogenous Ca2+ the incorporation of labelled UTP into the nuclei is stimulated in the denervated muscle and is inhibited in the control. Electrostimulation of the denervated muscle at the peripheral part of the sciatic nerve for 3 hrs increases both the RNA synthesis in the nuclei and the Ca2+ content, as well as the Ca, Mg-ATPase activity. Exogenous Ca2+ has an inhibitory effect on the nuclei of the stimulated muscle. The correlation established is indicative of participation of Ca2+ in the transmission of excitation in skeletal muscle sarcolemma to the processes occurring in nuclear structures.

Animals↗
PubMedDate not supplied

[The effect of catecholamines on the Ca2(+)-adenosinetriphosphatase of the sarcoplasmic reticulum in the skeletal muscles in chicken ontogeny].

It has been shown that the activity of Ca(2+)-ATPase increases during development. Epinephrine in vivo increases the activity of Ca(2+)-ATPase in chick skeletal muscles. The effect of hormone is lacking at embryonic stages of development and appears only before hatching. In the presence of exogenous protein kinase, cAMP also increases the activity of the enzyme, this effect being observed also in embryonic muscles. Lack of effect of epinephrine on Ca(2+)-ATPase in embryonic muscles is associated with non-reactivity of their adenylate cyclase to catecholamines. Ca(2+)-ATPase itself already at embryonic period is ready to react to cAMP. It is concluded that Ca(2+)-ATPase of sarcoplasmic reticulum is one of the sites of action of catecholamines on calcium metabolism in muscle cell and that this action is realized via the system adenylate cyclase-cAMP-protein kinase.

Animals↗