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 effects of adrenalectomy or nephrectomy, carried out one hour previously, on the levels of endogenous digitalis-like factors were determined in rat plasma. Factors were assayed by digoxin-like immunoreactivity and direct Na+,K(+)-ATPase inhibitory activity. Digoxin-like immunoreactivity significantly decreased one hour after bilateral ablation of adrenals, while Na+,K(+)-ATPase inhibitory activity remained unaltered. There were no changes in either activity one hour after bilateral nephrectomy. These results suggest that digoxin-like immunoreactivity may be derived from the adrenal gland or under adrenal control and the major substances detected by digoxin-like immunoreactivity and direct Na+,K(+)-ATPase inhibitory activity may be different.
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PMID:Further evidence for the dissociation of digoxin-like immunoreactivity from Na+,K(+)-ATPase inhibitory activity. 217 76

Retinal pigment epithelium (RPE)-choroid-sclera preparations from black dutch-belted rabbits were sealed in an Ussing chamber maintained at 37-39 degrees C. Typical preparations produced a spontaneous voltage (Ve) of 12.5 mV (retina side positive) and possessed an electrical resistance (R) of 350 ohm-cm2. Both of these values can be attributed to the RPE. Ouabain and amiloride diminished the Ve without affecting R. Ouabain was effective when applied to the apical but not to the basolateral side of the preparation, suggesting the presence of a Na-K ATPase on rabbit RPE apical membrane similar to that found in bullfrogs, embryonic chickens, cats and dogs. Dinitrophenol also reduced Ve. Digoxin, furosemide, bumetanide, ethacrynic acid and chlorothiazide had no apparent effect upon Ve and R. The lack of response to furosemide, bumetanide and ethacrynic acid strongly suggests that, unlike RPE from other species, rabbit RPE does not possess Na-dependent Cl transport and/or does not possess furosemide receptors on its apical membrane.
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PMID:Initial observations of rabbit retinal pigment epithelium-choroid-sclera preparations. 245 4

Digoxin-like inhibitors of Na,K-ATPase have been implicated in the pathophysiology of essential (EH) and pregnancy-induced hypertension (PIH). A technique that enhances dissociation of digoxin from red blood cells (RBC) was used to displace endogenous digoxin-like substances from RBCs. RBC membranes were preincubated in Na and ATP (Release) or Na,K,Mg and ATP (Retention) prior to measuring ATPase activity. Groups studied were: 39 men with EH and 34 controls plus 10 women with PIH and 17 normotensive controls. All displayed similar increases in Na,K-ATPase activity (24.0 +/- 7.9%) following Release. Plasma digoxin immunoreactivity (DI) was measured in pregnant women, m = 0.25 +/- 0.07 ng/ml. No DI was detected in nonpregnant women, but RBCs from these women demonstrated the same increase in Na,K-ATPase activity after Release. The 24% increase in activity achieved by Na and ATP preincubation can be reversed by adding K and Mg to the Release suspension. However, after RBC-bound digoxin is displaced by Release preincubation, addition of K and Mg cannot promote renewed binding and pump inhibition. Thus, the observed endogenous inhibition is not due to displacement of a digoxin-like substance but probably is related to alteration of the enzyme-membrane interaction. Furthermore, even though pregnant women demonstrate DI, an inhibitory substance with digoxin-like binding could not be recognized using this technique.
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PMID:Endogenous inhibition of red blood cell Na,K-ATPase in essential and pregnancy-induced hypertension. 255 44

Digoxin-like immunoreactive substance(s) (DLIS) was isolated from sera and autopsy-derived tissue obtained from premature and full-term neonates. The highest tissue level of DLIS was in the small bowel followed by the adrenal, gallbladder and liver. Of the fluids examined, meconium had the highest level of DLIS. Preparative high performance liquid chromatography fractionation of cord blood generated at least six different fractions which not only contained DLIS material but also inhibited canine kidney Na+/K+-ATPase activity. Recovery/inhibition studies indicated that 72% of the canine kidney Na+/K+-ATPase inhibition within one fraction could be accounted for on the basis of progesterone content of the fraction.
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PMID:A study into the nature and organ source of digoxin-like immunoreactive substance(s) in the perinatal period. 255 37

Atrial natriuretic peptide (ANP) and Na+ pump inhibitor (digitalis-like substance, DLS) have both been proposed to participate in body sodium and water homeostasis. Plasma levels and ANP and DLS have been reported to be increased in physiological or pathological states characterized by volume expansion. In order to investigate possible mutual relationships, their concentrations were measured in parallel during acute volume expansion by injection of 25 ml/kg isotonic NaCl (A) or blood (B) in the conscious rat. ANP was measured by radioimmunoassay and DLS by inhibition of renal Na+, K+-ATPase activity and digoxin-like immunoreactivity (DLI). Five minutes after injection, plasma ANP increased to reach 700 pg/ml (A, n = 21) or 1,500 pg/ml (B, n = 5) but the ability of plasma extracts to inhibit the renal Na+, K+-ATPase activity was unchanged (16.6 +/- 2.5 vs 16.9 +/- 2.0 p. 100, A, n = 8 and 6). Digoxin-like immunoreactivity was slightly lowered after NaCl injection from (74.4 +/- 6.2 to 65.4 +/- 5.1 pg/ml, n = 21) and unchanged after blood injection (79.0 +/- 3.4 vs 81.2 +/- 5.0 pg/ml, n = 5). Plasma ANP concentrations then decreased and had returned to preinjection values before 30 (A) or 90 (B) minutes, whereas the capacity of plasma to inhibit the Na+, K+-ATPase tended to increase (25.9 +/- 4.7 p. 100 at 3 hours after injection, n = 12 compared to 17.6 +/- 1.6 p. 100, n = 20) and DLI remains stable.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Variations in the plasma concentrations of atrial natriuretic factor and endogenous digitalis compounds during acute volume expansion in the conscious rat]. 284 69

Digoxin-like immunoreactive substances, which cross-react with digoxin antibody, have been found to have natriuretic effect and Na+,K+-ATPase inhibitory effect. The role of digoxin-like immunoreactive substances in chronic liver disease was studied by radioimmunoassay in 63 serum and 60 urine samples from 58 patients with chronic liver disease and compared with 16 controls. Although the mean serum digoxin-like immunoreactive substances level of compensated chronic liver disease patients (0.06 +/- 0.05 ng per ml, p less than 0.01) was higher than that of controls (0.02 +/- 0.03 ng per ml), only four patients had serum digoxin-like immunoreactive substances higher than 0.10 ng per ml. Mean serum digoxin-like immunoreactive substances level was much higher in patients with decompensated chronic liver disease who had ascites (0.32 +/- 0.17 ng per ml, p less than 0.001), hepatorenal syndrome (0.57 +/- 0.20 ng per ml, p less than 0.001) and hepatic encephalopathy (0.43 +/- 0.20 ng per ml, p less than 0.001). Five patients with recent variceal hemorrhage requiring transfusions and saline infusion had significantly increased serum digoxin-like immunoreactive substances (mean: 0.16 +/- 0.06 ng per ml, p less than 0.001) before the development of clinically detectable ascites.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Digoxin-like immunoreactive substances in chronic liver disease. 292 Sep 92

Digoxin-like immunoreactive substances (DLIS) have been successfully extracted and concentrated from cord serum, mixed (cord and maternal) serum and placentas. Similar substances have also been extracted from normal adult serum, but DLIS in this medium are present in much lower concentrations. Concentrated DLIS have been separated into several immunoreactive fractions by use of reverse-phase high-performance liquid chromatography. Immunoreactive fractions were tested for their ability to inhibit the Na+,K+-ATPase by measuring the 86Rb-uptake of red blood cells in the presence of these fractions. A potent inhibitor was identified in an immunoreactive fraction which also contains progesterone, but the results suggest that the pump inhibitor is not progesterone. Cross-reactivity studies utilising fluorescence polarization immunoassay have shown that cortisone is the most potent immunoreactive substance of cord serum.
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PMID:Digoxin immunoreactivity in cord and maternal serum and placental extracts. Partial characterization of immunoreactive substances by high-performance liquid chromatography and inhibition of Na+, K+-ATPase. 298 94

A simplified method for the determination of natriuretic factor in the urine as measured by digoxin-like substance was studied. Digoxin-like substance in the urine was estimated by RIA using anti-digoxin antibody after being extracted by reversed phase cartridge column but without gel filtration. The values found by radioimmunoassay (RIA) yielded a significant correlation with those of the inhibitory effect of Na-K-ATPase activity which was measured by biochemical assay as described by Hamlyn et al. Using this RIA method, the effect of salt intake on natriuretic factor in urine was studied in patients with essential hypertension. The natriuretic factor on a high sodium diet (NaCl 20 g/day for three days) increased approximately 1.5 times, as compared to those on a low sodium diet (NaCl 3 g/day) (p less than 0.05). The Natriuretic factor showed a positive correlation with urinary Na excretion (P less than 0.050) when the patients were placed on ad. lib. sodium diet. From these results, it is suggested that secretion of natriuretic factor in the urine might be regulated in part by salt intake.
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PMID:Effect of sodium intake on the excretion of urinary natriuretic factor in essential hypertensives. 299 16

Ventricular muscle of rat heart has two classes of receptors which are responsible for the positive inotropic effect of ouabain. Low affinity receptors are apparently related to Na+, K+-ATPase. To determine if high affinity receptors are also sarcolemmal Na+, K+-ATPase of muscle cells, their characteristics were examined. Binding of [3H]ouabain to the high affinity binding site required ATP in the presence of Mg2+ and Na+, was stimulated by Na+ in the presence of Mg2+ and ATP, and was inhibited by K+. Digoxin, digitoxin and cassaine all inhibited [3H]ouabain binding to the high affinity site. Cassaine was about an order of magnitude less potent than the glycosides. These results indicate similarities in high affinity ouabain binding sites in ventricular muscle of rat heart and Na+, K+-ATPase obtained from other sources. Destruction of sympathetic nerve terminals with 6-hydroxydopamine failed to affect the high affinity ouabain binding sites indicating that high affinity sites do not represent the Na+, K+-ATPase in sympathetic nerve terminals. Labeling of Na+, K+-ATPase from [gamma-32P]ATP indicates that high affinity ouabain binding sites account for 25% of the total enzyme molecules present in ventricular muscle of rat heart.
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PMID:High affinity and low affinity ouabain binding sites in the rat heart. 302 36

Digoxin could improve diaphragm contractility and fatigability if inhibition of sodium-potassium adenosine triphosphatase enhances calcium influx from extracellular sources, or it could impair contractility and worsen fatigue if it impairs maintenance of the membrane potential. We studied the effects of digoxin on isometric force production, fatigue, and recovery in isolated, directly stimulated, guinea pig and rat diaphragms. Digoxin had no effect on maximal twitch or tetanic tensions compared with control diaphragms in either rat (2 ng/ml to 20 micrograms/ml) or guinea pig (2 ng/ml to 2 micrograms/ml) hemidiaphragms. Digoxin worsened high frequency fatigue and impaired recovery from fatigue in guinea pigs (200 ng/ml to 2 micrograms/ml) but not in rat (2 micrograms/ml) hemidiaphragms. We conclude that digoxin has no effect on diaphragm contractility. Hypopolarization of the membrane potential is the likely cause for the increased fatigability. The difference in responsiveness between species is likely due to insensitivity of rat sodium-potassium adenosine triphosphatase to digoxin.
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PMID:The effect of digoxin on contractility and fatigue of isolated guinea pig and rat hemidiaphragms. 320 78


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