Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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 binding of insulin and insulin-like growth factor I (IGF-I) and their effect on amino acid and neurotransmitter transport was studied in cultured human Y79 retinoblastoma cells. Y79 cells possess specific receptors for both insulin and IGF-I. Insulin binding to Y79 cells is characterized by a curvilinear Scatchard plot suggesting a two-site or two-affinity binding system. In contrast, IGF-I binding has a linear plot indicative of a one-site, one-affinity binding system. The uptake of glycine, a putative neurotransmitter in the retina occurs by a specific transport system in Y79 cells, independent of the uptake of other neutral amino acids. The uptake of glycine was increased 25-50% by either insulin or IGF-I. The response to insulin or IGF-I on glycine uptake is gradual and concentration dependent. The accumulation of other amino acids and putative retinal neurotransmitters by Y79 cells was not significantly affected by insulin of IGF-I. In addition, the activity of Na+/K+-ATPase was not influenced. The analysis of high affinity glycine uptake indicates that insulin and IGF-I are stimulating glycine transport by increasing the V'max without significantly affecting the K'm. Further analysis suggests that insulin and IGF-I are causing a recruitment of additional glycine transporters at the cell surface or activating otherwise nonfunctional transporters by an unexplained mechanism. Because of the implication that glycine responds as a neuroactive amino acid in Y79 cells these studies suggest that insulin and IGF-I may influence neuroactivity in the human retina by regulating the transport of glycine.
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PMID:Amino acid and putative neurotransmitter transport in human Y79 retinoblastoma cells. Effect of insulin and insulin-like growth factor. 288 1

The inhibition of glycolysis in tumor cells by methionine requires that the cells be incubated with methionine for several hours in the presence of serum. We now show that in the case of confluent rat-1 fibroblasts transfected with the ras gene the serum can be substituted by insulin and insulin-like growth factor I or II. No other growth factor tested was effective. In subconfluent ras cells additional growth factors (transferrin and high density lipoproteins) were required for maximal inhibition of glycolysis by methionine. Exploration of the mechanism of action of methionine revealed that the accumulation of [35S]methionine into rat-1 fibroblasts was only marginally increased by insulin. We propose that methionine inhibits an adenosine triphosphatase activity because addition of low concentrations of Nonidet P-40 greatly enhanced glycolysis even in the presence of methionine, suggesting that it did not affect the glycolytic enzymes directly. Methionine also affected growth both in monolayer and soft agar. Rat-1 fibroblasts transfected with the ras gene were markedly more sensitive to methionine than cells transfected with the myc gene.
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PMID:Effect of growth factors and methionine on glycolysis and methionine transport in rat fibroblasts and fibroblasts transfected with myc and ras genes. 308 Dec 58

Insulin augments the activity of Na(+)-K(+)-adenosinetriphosphatase (ATPase) in skeletal muscles. This study shows that when furosemide- and bumetanide-inhibitable 86Rb+ uptake is measured in the skeletal muscle-like BC3H1 cell line, insulin and insulin-like growth factor I (IGF-I) activate a loop diuretic-sensitive K+ and Cl- transport system but have no effect on Na(+)-K(+)-ATPase. The insulin-stimulated K+ transport system is extracellular Na+ concentration ([Na+]o) independent and extracellular Cl- concentration ([Cl-]o) dependent. Na(+)-independent K(+)-Cl- cotransport systems have been identified in other cells, but their sensitivity to insulin or growth factors has not been described. The affinities of the insulin-stimulated K+ uptake in BC3H1 cells for K+ (0.9 +/- 0.1 mM) and loop diuretics (5.9 x 10(-7) and 10(-7) M for furosemide and bumetanide, respectively) are higher than those of K(+)-Cl- cotransporters in other cells. Thus the insulin-stimulated K+ and Cl- transport system in BC3H1 seems kinetically different from K(+)-Cl- cotransporters in other cells. Insulin and IGF-I may activate a unique K(+)-Cl- cotransporter or activate a [Na+]o-independent K(+)-Cl- cotransport mode of Na(+)-K(+)-Cl- cotransporter in BC3H1 cells.
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PMID:Insulin activates furosemide-sensitive K+ and Cl- uptake system in BC3H1 cells. 794 88

To determine whether insulin regulates vascular smooth muscle Na+, K(+)-ATPase activity and if impaired insulin stimulation of vascular smooth muscle Na+, K(+)-ATPase activity could be a cause of increased vascular reactivity to norepinephrine and angiotensin II in diabetic states, the effects of insulin on Na+, K(+)-ATPase activity were examined in normal rabbit aortic intima-media incubated with normal plasma glucose and myo-inositol levels for 30 min. Insulin at 100 microU/ml (600 pmol/l) had no effect on Na+, K(+)-ATPase activity. At 250 microU/ml it caused a 4.2 +/- 0.8% increase, and at 500 microU/ml insulin caused a 17.7 +/- 1.4% increase in Na+, K(+)-ATPase activity that was completely inhibited by amiloride (1 mmol/l). Human insulin-like growth factor I (600 pmol/l) caused an 18.0 +/- 1.0% increase in Na+, K(+)-ATPase activity that was inhibited by amiloride. Insulin does not regulate (stimulate) aortic vascular smooth muscle Na+, K(+)-ATPase activity. Supraphysiological insulin concentrations, probably acting through an insulin-like growth factor I receptor, stimulate Na+/H+ exchange in aortic vascular smooth muscle and cause small secondary increases in Na+, K(+)-ATPase activity. In aortic intima-media incubated with normal plasma glucose and myo-inositol levels, endogenously released adenosine stimulates and maintains a component of resting Na+, K(+)-ATPase activity and stimulates acute increases in activity when norepinephrine (1 mumol/l) or angiotensin II (100 nmol/l) is added. These adenosine-stimulated components of Na+, K(+)-ATPase activity are selectively inhibited when the medium glucose is raised to 30 mmol/l during a 30-min equilibration and 30-min incubation.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Insulin does not regulate vascular smooth muscle Na+, K(+)-ATPase activity in rabbit aorta. 838 38

The potential roles of growth hormone (GH) and insulin-like growth factor I (IGF-I) in seawater (SW) acclimation of juvenile Atlantic salmon (Salmo salar) were examined. Compared to controls, fish in 12 ppt seawater given one or three injections (2-6 days) of GH (ovine, 0.2 microgram.g-1) or IGF-I (recombinant bovine, 0.05-0.2 microgram.g-1) had significantly greater salinity tolerance as judged by lower plasma sodium, osmolality, and muscle moisture content following transfer to 34 ppt. Single injections of GH and IGF-I in fish in fresh water failed to improve salinity tolerance following transfer to 25 ppt SW. Treatment of fish in 12 ppt with GH or IGF-I for 2-6 days did not increase gill Na+, K(+)-ATPase activity, but treatment with GH prevented decreases in gill Na+, K(+)-ATPase activity that occurred in controls following transfer to 34 ppt seawater. Fish in fresh water administered GH by implants (5.0 microgram.g-1) or osmotic minipumps (0.5 micrograms.g-1 day-1) for 7-14 days had greater gill Na+, K(+)-ATPase activity and salinity tolerance than controls. IGF-I administered by implants (0.5-1.0 microgram.g-1) or osmotic minipumps (0.1 microgram.g-1 day-1) for 4-14 days did not increase salinity tolerance or gill Na+, K(+)-ATPase activity. Cortisol implants (50 micrograms.g-1) also increased gill Na+, K(+)-ATPase activity and salinity tolerance after 14 days, and in combination with GH had a synergistic effect, Although IGF-I and cortisol implants had no significant effect after 7 days, in combination they significantly increased gill Na+, K(+)-ATPase activity. The results indicate that GH and cortisol can increase salinity tolerance and gill Na+, K(+)-ATPase activity of Atlantic salmon and together act in synergy. Although IGF-I can increase salinity tolerance in short-term treatments (2-6 days) in 12 ppt, it is less effective than GH in increasing salinity tolerance and gill Na+, K(+)-ATPase activity in long-term treatments (7-14 days) and in interacting with cortisol.
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PMID:Effects of growth hormone and insulin-like growth factor I on salinity tolerance and gill Na+, K+-ATPase in Atlantic salmon (Salmo salar): interaction with cortisol. 871 39

In skeletal muscle, the Na+, K+ pump is predominantly situated in the sarcolemma (1000-3500 pumps per microns 2). The total concentration can be determined in fresh or frozen biopsies (1-5 mg) using a 3H-ouabain binding assay. The values obtained have been confirmed by measurements of maximum ouabain suppressible Na+, K(+)-transport capacity in intact muscles as well as Na+, K(+)-ATPase-related enzyme activity in muscle homogenates. In the mature organism, the concentration of Na+, K+ pumps varies with muscle type and species in the range 150-600 pmol (g wet wt)-1 in rat and human muscle, the concentration increases markedly with thyroid status. Semi-starvation and untreated diabetes reduce the concentration by 20-48%. K+ deficiency leads to a downregulation of up to 75%. Both in animals and in humans, training increases the concentration of Na+, K+ pumps in muscle and inactivity leads to a downregulation. High-frequency stimulation elicits up to a 20-fold increase in the net efflux of Na+ within 10 s This is the major activation mechanism for the Na+, K+ pump, utilizing its entire capacity and possibly represents a drive on de novo synthesis of Na+, K+ pumps. A variety of hormones (insulin, insulin-like growth factor I, adrenaline, noradrenaline, calcitonin gene-related peptide, calcitonin, amylin) increase the rate of active Na+, K+ transport by 60-120% within a few minutes. This leads to a decrease in intracellular Na+ and hyperpolarization. In isolated muscles, where contractility is inhibited by high extracellular K(+)- such agents produce rapid force recovery. which is entirely suppressed by ouabain and closely correlated to the stimulation of K+ uptake and the decline in intracellular Na+. The observations support the conclusion that the Na+, K+ pump plays a central role in the acute recovery and maintenance of excitability during contractile activity.
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PMID:The Na+, K+ pump in skeletal muscle: quantification, regulation and functional significance. 872 82

To evaluate GH's role in cardiac physiology and its interrelationship with the beta-adrenergic system, we studied GH-deficient dwarf (dw/dw) and control rats in 4 groups of 20 each: dwarf group receiving placebo, dwarf-GH group receiving 2 mg/kg GH, dwarf-GH-propranolol group receiving 2 mg/kg GH and 750 mg/liter propranolol, and a control group of Lewis rats receiving placebo. Dwarf rats showed reduced left ventricular weight and myocyte cross-sectional area, and impaired cardiac performance in vitro. Left ventricular pressure-volume curves showed a shift upward and leftward, indicating reduced distensibility. These abnormalities reversed after GH treatment regardless of concomitant propranolol administration. Although isoproterenol responsiveness was reduced in dwarf rats, there were no differences in beta-adrenergic receptor density, affinity, Na+,K+-adenosine triphosphatase activity, or adenylyl cyclase activity. In summary, myocyte size, cardiac structure, myocardial contractility, and distensibility are abnormal in GH deficiency. The effects of GH are not mediated by the beta-adrenergic pathway, which, in turn, is unaffected by changes in the GH-insulin-like growth factor I axis. Thus, GH plays a regulatory role in normal cardiac physiology that is independent of the beta-adrenergic system.
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PMID:Consequences of growth hormone deficiency on cardiac structure, function, and beta-adrenergic pathway: studies in mutant dwarf rats. 938 96

The ability of ovine growth hormone (oGH), recombinant bovine insulin-like growth factor I (rbIGF-I), recombinant human insulin-like growth factor II (rhIGF-II), and bovine insulin to increase hypoosmoregulatory capacity in the euryhaline teleost Fundulus heteroclitus was examined. Fish acclimated to brackish water (BW, 10 ppt salinity, 320 mOsm/kg H2O) were injected with a single dose of hormone and transferred to seawater (SW, 35 ppt salinity, 1120 mOsm/kg H2O) 2 days later. Fish were sampled 24 h after transfer and plasma osmolality, plasma glucose, and gill Na+, K+-ATPase activity were examined. Transfer from BW to SW increased plasma osmolality and gill Na+,K+-ATPase activity. Transfer from BW to BW had no effect on these parameters. rbIGF-I (0.05, 0.1, and 0.2 microg/g) improved the ability to maintain plasma osmolality and to increase gill Na+, K+-ATPase activity in a dose-dependent manner. oGH (0.5, 1, and 2 microg/g) also increased hypoosmoregulatory ability but only the higher doses (2 microg/g) significantly increased gill Na+,K+-ATPase activity. oGH (1 microg/g) and rbIGF-I (0.1 microg/g) had a significantly greater effect on plasma osmolality and gill Na+,K+-ATPase activity than either hormone alone. rhIGF-II (0.05, 0.1, and 0.2 microg/g) and bovine insulin (0.01 and 0.05 microg/g) were without effect. The results suggest a role of GH and insulin-like growth factor I (IGF-I) in seawater acclimation of F. heteroclitus. Based on these findings and previous studies, it is concluded that the capacity of the GH/IGF-I axis to increase hypoosmoregulatory ability may be a common feature of euryhalinity in teleosts.
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PMID:Evidence for growth hormone/insulin-like growth factor I axis regulation of seawater acclimation in the euryhaline teleost Fundulus heteroclitus. 967 82

The effects of senescence on muscle characteristics and the insulin-like growth factor I (IGF-I) pathway were assessed in male and female BN/F344 rats. The mass and total ATPase activity of gastrocnemius and plantaris muscles were reduced with age and to a greater extent in males than in females. The mass and total ATPase activity of soleus muscle were not significantly altered with age. Circulating IGF-I was also significantly reduced with age, 60% in females and 21% in males. Circulating IGF-binding protein 3 (IGFBP-3) was reduced with age. In liver and gastrocnemius muscle, mRNAs for IGF-1, IGFBP-2, and IGFBP-3 were analyzed in young and aged males of two strains, BN/F344 and Sprague-Dawley. In BN/F344 rats, liver mRNAs were unchanged with age. Also in BN/F344 rats, muscle mRNAs for IGFBP-2, and IGFBP-3 displayed nonsignificant trends toward increase with age. In aged Sprague-Dawley males, liver mRNA for IGF-I was increased 15% and muscle mRNA for IGFBP-2 was increased 110%. Thus, different age-related changes in the growth hormone (GH)/IGF pathway occur in males and females between the sexes and strains. These changes may play a role in the muscle atrophy associated with senescence.
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PMID:Altered IGF-I and IGFBPs in senescent male and female rats. 1019 34

The objective of this study was to investigate the effects of insulin and insulin-like growth factor I on transepithelial Na(+) transport across porcine glandular endometrial epithelial cells grown in primary culture. Insulin and insulin-like growth factor I acutely stimulated Na(+) transport two- to threefold by increasing Na(+)-K(+) ATPase transport activity and basolateral membrane K(+) conductance without increasing the apical membrane amiloride-sensitive Na(+) conductance. Long-term exposure to insulin for 4 d resulted in enhanced Na(+) absorption with a further increase in Na(+)-K(+) ATPase transport activity and an increase in apical membrane amiloride-sensitive Na(+) conductance. The effect of insulin on the Na(+)-K(+) ATPase was the result of an increase in V(max) for extracellular K(+) and intracellular Na(+), and an increase in affinity of the pump for Na(+). Immunohistochemical localization along with Western blot analysis of cultured porcine endometrial epithelial cells revealed the presence of alpha-1 and alpha-2 isoforms, but not the alpha-3 isoform of Na(+)-K(+) ATPase, which did not change in the presence of insulin. Insulin-stimulated Na(+) transport was inhibited by hydroxy-2-naphthalenylmethylphosphonic acid tris-acetoxymethyl ester [HNMPA-(AM)(3)], a specific inhibitor of insulin receptor tyrosine kinase activity, suggesting that the regulation of Na(+) transport by insulin involves receptor autophosphorylation. Pretreatment with wortmannin, a specific inhibitor of phosphatidylinositol 3-kinase as well as okadaic acid and calyculin A, inhibitors of protein phosphatase activity, also blocked the insulin-stimulated increase in short circuit and pump currents, suggesting that activation of phosphatidylinositol 3-kinase and subsequent stimulation of a protein phosphatase mediates the action of insulin on Na(+)-K(+) ATPase activation.
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PMID:Insulin stimulates transepithelial sodium transport by activation of a protein phosphatase that increases Na-K ATPase activity in endometrial epithelial cells. 1049 74


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