Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.6.1.3 (ATPase)
 65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The authors determined total and specific activity (Ca2+, Mg2+) ATPase in homogenates of uterus muscle, placenta, amnion and chorion. The material was also studied for the levels of ATP, ADP and AMP in order to evaluate the energetic potential. The research was carried out in two groups: among 23 pregnant women who underwent Cesarean section not accompanied by labour pains and among 30 women in labour in whom labour pains lasted up to six hours and then labour was completed by Cesarean section. It was found that in advanced pregnancy the highest enzyme activity is in chorion homogenates. Labour pains result in decrease in enzyme activity in the material studied; the highest significant decrease observed in chorion. It was also found that labour pains do not result in greater changes in energetic potential of tissues except for chorion and amnion. The results obtained point to particular participation of chorion in the process of active transportation of calcium ions in pregnancy and delivery. The consequence of change in enzyme activity will be changes in the level of Ca2+ ions, which will result in the activation or inhibition of various metabolic tracts on cellular level, including hormonal changes.
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PMID:[Calcium magnesium ATPase activity in homogenates of the placenta and myometrium of pregnant women and parturients]. 252 98

We describe the characterization of a rat kidney cDNA that encodes a novel Ca2+-transporting ATPase. The cDNA, termed RK 8-13, was isolated previously using an oligonucleotide hybridization probe corresponding to part of the ATP binding site of the sarcoplasmic reticulum Ca-ATPases (Gunteski-Hamblin, A.-M., Greeb, J., and Shull, G. E. (1988) J. Biol. Chem. 263, 15032-15040). The complete nucleotide sequence of the 4.5-kilobase cDNA has been determined, and the primary structure of the protein has been deduced. The enzyme consists of 999 amino acids, has an Mr of 109,223, and contains all of the conserved domains found in transport ATPases of the E1-E2 class. It exhibits 75-77% amino acid identity with the fast-twitch and slow-twitch/cardiac isoforms of the sarcoplasmic reticulum Ca-ATPase, and the hydropathy plots of the three enzymes are virtually identical. High levels of ATP-dependent Ca2+ uptake were demonstrated in microsomes of COS-1 cells that had been transfected with a construct consisting of the entire coding sequence of the cDNA in the expression vector p91023(B). Northern blot analyses of poly(A)+ RNA revealed that the mRNA for this protein is expressed in heart, skeletal muscle, uterus, brain, lung, liver, kidney, testes, small intestine, large intestine, and pancreas. These data show that the enzyme is a Ca2+-transporting ATPase and that its mRNA is expressed in a broad variety of both muscle and non-muscle tissues.
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PMID:cDNA cloning, functional expression, and mRNA tissue distribution of a third organellar Ca2+ pump. 255 13

1. Na/K ATPase activity in rat myometrial cells in culture exhibited a Kapp of 0.93 mM for Rb+ and a Ki of 31 microM for ouabain with respect to Rb+. 2. 86Rb+ uptake was stimulated by serum and monensin but was not affected by the uterine relaxants isoproterenol and relaxin in 0.5-7.5 mM Rb+. Nonetheless, these relaxants elicited significant increases in 45Ca2+ efflux under similar conditions. 3. These data suggest that increased Na/Ca exchange resulting from a stimulation of Na/K ATPase is not involved in the mechanism of action of relaxin and isoproterenol in the uterus.
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PMID:Rat myometrial Na/K ATPase is increased by serum but not by isoproterenol and relaxin. 257 89

ATPase activity of uterus and ovary was markedly elevated in presence of gossypol and decreased in presence of lactic acid indicating activation and inhibition of energy metabolism by gossypol and lactic acid respectively. The elevated levels of glycogen in uterus indicate inhibition of glycogenolysis as supported by phosphorylase activity. Whereas in ovary the glycogen depletion indicates activation of glycogenolysis supported by phosphorylase activity. The activity levels of aldolase and G-6-PDH decreased in the uterus in presence of gossypol and increased in presence of lactic acid. The same were elevated in ovary indicating the activation of hexose mono and diphosphate pathways. Lactic acid accumulated in presence of both gossypol and lactic acid with a depletion in level of pyruvic acid in both the tissues. This situation in the uterus indicates the condition of anti-implantation in presence of both gossypol and lactic acid. The NAD-LDH activity was inhibited in presence of gossypol and activated in presence of lactic acid in both tissues.
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PMID:In vitro effects of gossypol and lactic acid on rat uterus and ovary during implantation and antiimplantation. 263 59

Maternal endoxin (digoxinlike substance) is proposed as arising in the fetal area of the fetal adrenal cortex. Its function may be to sensitize the uterus for labor, much as does cortisol in the sheep fetus. Because endoxin is a sodium-potassium-adenosine triphosphatase inhibitor, however, it may also induce maternal vasoconstriction. On our service, normal pregnant women have detectable endoxin after 35 weeks with increasing amounts at term. Specimens of cord blood often have "digoxin" in the therapeutic range. We find that about 40% of women in premature labor and 65% of pregnant women with hypertension have elevated levels of serum endoxin. Postdate gravid women sometimes have very low endoxin levels. Pregnant women with complications and elevated digoxin (endoxin) levels could have specific antidigoxin therapy if endoxin proves to be a modulator of their symptoms. Digoxinlike substances are also sometimes elevated in ill nonpregnant persons, such as those with renal, liver, or heart failure, or hypertension.
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PMID:Fetal endoxins and complications of pregnancy. 284 75

Sodium vanadate reversed cooling-induced relaxation of K-depolarized taenia coli of guinea-pigs but failed to reverse it in the portal vein and uterus. It potentiated cooling-induced contraction of K-depolarized vas deferens and ureter. These effects were not mediated by the inhibition of Na,K-ATPase, but by the inhibition of the Ca-pump.
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PMID:Effect of vanadate on cooling-induced tension changes in K-depolarized smooth muscles from guinea-pigs. 289 32

Native thin filaments were extracted from rabbit uterus by the procedure of Marston and Smith. The protein content was actin, tropomyosin, and caldesmon in molar ratios of 1:0.2:0.03. Some filamin, myosin, and calcium-binding protein were also present. The thin filaments activated skeletal or smooth muscle myosin magnesium adenosine triphosphatase at least 30-fold. Activation was regulated by Ca2+; maximum observed Ca2+ sensitivity was greater than 10 times. The thin filaments were dismantled into component proteins by the method of Smith and Marston. Actin and actin-tropomyosin-activated myosin magnesium adenosine triphosphatase, but the activation was not Ca2+-regulated. Added caldesmon inhibited adenosine triphosphatase activation by as much as 80%, with 50% inhibition at 1 caldesmon per 50 actin. Caldesmon inhibition was not Ca2+ dependent, but inhibition could be reversed by further addition of Ca2+ and calmodulin. It is concluded that the thin filaments of uterine smooth muscle are Ca2+ regulated and that this regulatory system could be involved in control of uterine smooth muscle contractility. A mechanism for thin filament regulation, mediated by caldesmon, is proposed.
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PMID:Calcium ion-dependent regulation of uterine smooth muscle thin filaments by caldesmon. 291 89

Because of the potential of dihydropyridine calcium channel blockers in the management of premature labor, we have studied the direct effects of nitrendipine on actomyosin in the pregnant and nonpregnant uterus and in the term human placenta. Actomyosin adenosinetriphosphatase in the three tissues and another model of actin-myosin interaction, superprecipitation of placental actomyosin, were inhibited by nitrendipine. The inhibition was not diminished by high concentrations of calcium. To identify the mechanism, placental myosin was phosphorylated in the absence and presence of 0.8 X 10(-4) mol/L of nitrendipine. The myosin phosphorylated in the presence of nitrendipine had lower actin-activated adenosinetriphosphatase, which is consistent with the inhibition of myosin light chain phosphorylation. However, nitrendipine did not affect the adenosinetriphosphatase activity of myosin nor did further reduce the adenosinetriphosphatase of the already phosphorylated placental actomyosin. Thus nitrendipine inhibition is directed to the phosphorylation reaction but not to the adenosinetriphosphatase site of myosin. Myometrial relaxation in vivo or in vitro occurs at the pharmacologic nitrendipine levels of 10(-9) to 10(-8) mol/L, which is at least 10,000 times lower than that of the concentration of 50% inhibition of myosin light chain phosphorylation (0.0026 +/- 0.00015 mol/L of nitrendipine, mean +/- SEM) demonstrated in the present work. Because of this difference, the direct intracellular actions of dihydropyridine calcium channel blockers are not expected to cause adverse effects in the uteroplacental system when these drugs are used in the prevention or treatment of premature labor.
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PMID:Pharmacologic levels of nitrendipine do not affect actin-myosin interaction in the human uterus and placenta. 293 50

In order to clarify the biochemical bases of myometrial contractions, (Ca2+-Mg2+)-ATPase activity, actomyosin (ACT)-ATPase activity and ACT superprecipitation were studied during pregnancy. The results indicate that; (Ca2+-Mg2+)-ATPase activity in nonpregnant ovariectomized rats was markedly increased after estradiol treatment (15 micrograms/day for 3 days) from 12.0 +/- 20.1 to 132.5 +/- 22.8 nmolePi/mg/min (p less than 0.01). The activity on days 19, 20, 21 and 22 of pregnancy was 48.0 +/- 5.0, 48.2 +/- 7.5, 112.3 +/- 18.5 and 27.3 +/- 8.8 nmolePi/mg/min, respectively, showing marked prepartum increase and rapid decrease after delivery. In human myometrium, basal (Ca2+-Mg2+)-ATPase activity showed no significant change but at term the activity was decreased (79.4 +/- 9.8 to 60.7 +/- 7.4 nmolePi/mg/min, p less than 0.05) in the presence of calmodulin (CMD). Human myometrial ACT-ATPase activity, on the other hand, was stimulated with CMD (1st trimester, term without labor and with labor: 295 to 1,134, 550 to 1,243 and 897 to 4,735 pmolePi/mg/min, p less than 0.05). Myometrial CMD concentrations, however, showed no change during pregnancy. ACT prepared from rabbit uterus showed an enhanced interaction of contractile proteins in the presence of CMD. These data indicate that CMD stimulates (Ca2+-Mg2+)-ATPase activity in early pregnancy but inhibits at term and increases ACT-ATPase activity. Since the myometrial CMD concentration remains unchanged during pregnancy, there may exist a function which alters CMD action on ATPase activity as pregnancy advances.
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PMID:[A study of (Ca2+-Mg2+)-, and actomyosin-ATPase activities in pregnant myometrium and the functional modification by calmodulin]. 294 43

Crude extracts of taenia coli (guinea-pig), gizzard (chicken), stomach, colon, ureter, bladder, mesenteric vein, mesenteric artery, uterus and vas deferens (dog) were electrophoresed under conditions which do not denature myosin (pyrophosphate gels). Two isozymes (G1 and G2) were observed in all cases. Their mobilities are the same in all organs, but there are some variations in their relative proportions. They have an ATPase activity. Based on electrophoretic mobility the light chains (L20 and L17) seem to be the same for both isozymes whilst the heavy chains are different. Isozyme G2 contains one type of heavy chain of an apparent molecular mass of 230 kDa, whilst isozyme G1 contains two types of heavy chains: one of apparent molecular mass of 230 kDa, and the other of apparent molecular mass of 200 kDa.
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PMID:Detection and distribution of myosin isozymes in vertebrate smooth muscle. 299 31


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