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)

1. Six rat liver plasma-membrane subfractions of different density and morphological, enzymic and chemical properties were prepared from homogenates by a combination of differential, rate-zonal and density-gradient centrifugation. They consisted of three vesicular 'light' subfractions of density 1.12-1.13 and three 'heavy' subfractions of density 1.16-1.18 containing membrane strips and intercellular junctions. 2. All six subfractions contained a basal adenylate cyclase activity. One of the 'light' subfractions that showed the highest glucagon-stimulated adenylate cyclase activity was identified as deriving form the blood-sinusoidal face of the hepatocyte. This subfraction, unlike the others, was contaminated by Golgi components, as indicated by its morphological properties and the presence of galactosyl- and sialyl-transferase activities. 3. All the six subfractions showed high activities of the following plasma-membrane marker enzymes: 5'-nucleotidase, alkaline phosphodiesterase (nucleotide pyrophosphatase), alkaline phosphatase, leucine naphthylamidase and Mg2+-activated adenosine triphosphatase. A 'light' subfraction that showed the highest specific activities of all the above marker enzymes, but lacked a glucagon-stimulated adenylate cyclase activity, was identified as deriving from the bile-canalicular face of the hepatocyte. 4. The 'heavy' subfractions, which showed generally the lowest activities of the above plasma-membrane enzyme markers, and were characterized by the presence of desmosomes and gap junctions, were taken to originate from the contiguous faces of the hepatocyte. 5. The protein composition of the six subfractions was generally similar, as shown by polyacrylamide-gel electrophoresis. Differences in the amounts of various protein and glycoprotein bands among the subfractions correlated with their morphology, enzymic composition and sialic acid content. 6. Hormonal and histochemical evidence supporting the identification of a bile-canalicular subfraction, a blood-sinusoidal subfraction and contiguous-face subfractions is discussed.
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PMID:Functional polarity of the rat hepatocyte surface membrane. Isolation and characterization of plasma-membrane subfractions from the blood-sinusoidal, bile-Canalicular and contiguous surfaces of the hepatocyte. 12 84

Sodium-potassium-activated adenosine triphosphatase (Na-K-ATPase) is associated with electrolyte transport in many tissues. To help delineate its role in intestinal transport, changes in rat intestinal electrolyte and water transport induced by injecting methylprednisolone acetate 3 mg/100 g or deoxycorticosterone acetate (DOCA) 0.5 mg/100 g per day for 3 days were correlated with changes in Na-K-ATPase activity. Methylprednisolone increased sodium and water absorption, potassium secretion, transmural potential difference, and Na-K-ATPase activity in the jejunum, ileum, and colon. Examination of isolated epithelial cells demonstrated that the jejunal and ileal increase in Na-K-ATPase occurred in both the villus tip and crypermeability, Mg-ATPase, and adenylate cyclase activities were unchanged by methylprednisolone. DOCA increased sodium and water absorption, potassium secretion, transmural potential difference, and Na-K-ATPase activity in the colon alone. Colonic Mg-ATPase and adenylate cyclase activities were unaffected. Jejunal and ileal enzyme activity, electrolyte transport, and permeability were unchanged by DOCA. Methylprednisolone and DOCA were not additive in their effect on colonic Na-K-ATPase activity. Methylprednisolone and DOCA increased electrolyte and water transport and Na-K-ATPase activity concomitantly in specific segments of small intestine and colon. These data are consistent with an important role for Na-K-ATPase in intestinal electrolyte and water transport.
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PMID:Na+-K+-activated adenosine triphosphatase and intestinal electrolyte transport. Effect of adrenal steroids. 12 64

Cardiomyopathic hamsters (UM-X7.1) show clinical signs of congestive heart failure and an abnormal EKG pattern. The sarcolemmal fraction obtained from the failing hearts at advanced stages of myopathy exhibited no change in the basal adenylate cyclase activity; however, the activity of this enzyme in the presence of catecholamines or NaF was lower in the failing heart sarcolemma than that in the control. The activities of Ca2+-ATPase, Mg2+-ATPase, and Na+-K+-ATPase in the failing heart sarcolemma were also less than the control values. These results suggest an association of membrane defect with heart failure.
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PMID:Membrane alteration in failing hearts of cardiomyopathic hamsters. 12 77

The adenylate cyclase activity from a rat liver plasma membrane preparation was inhibited by low concentrations (1-10 muM) of the mercurial diuretic mersalyl. Complete inhibition was obtained with 0.1 mM mersalyl. Similar effects were observed whether the adenylate cyclase preparation was assayed in the presence of 10 muM GTP, 0.1 muM glucagon, 10 mM NaF or without any addition. The effect of mersalyl was not due to inhibition of the regenerating system present in the incubation medium, since the effect of mersalyl was preserved and even enhanced in its absence. The inhibition brought about by mersalyl was due to both a decrease of the maximal velocity of the reaction and of the affinity of the enzyme for the substrate. It was immediate, and irreversible spontaneously, but it was reversed by the simultaneous additions of 2-mercaptoethanol, in a dose-dependent fashion. Other -SH reagents were found to have an effect equal to, or lower than, that of mersalyl. Mersalyl had no effect upon Mg2+-ATPase, although it inhibited the (Na+-K+) activated ATPase. Since mersalyl is known to be a 'non-penetrant' reagent, it is postulated that a catalytically important, mercurial-sensitive, part of adenylate cyclase is at the surface of the plasma membrane. This view is supported by the following facts: (a) mersalyl acted with a similar dose-response curve upon an intact as well as a detergent-dispersed cyclase preparation while no effect was observed upon a solubilized Mg2+-ATPase preparation; (b) a covalent p-chloromercuribenzoate-Sephadex preparation (but not its supernatant) inhibited the cyclase from intact membranes. It is proposed that mercurial derivatives, by their relative specificity of action (no effect on Mg2+-ATPase), can serve as useful probes in the elucidation of the multicomponent structure of the cyclase system.
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PMID:Adenylate cyclase from rat-liver plasma membrane: inhibition by mersalyl and other mercurial derivatives. 12 56

Two highly lead-sensitive ATPases, Na+,K+-ATPase and adenylate cyclase, can be demonstrated cytochemically by the lead precipitation technique in briefly prefixed tissue, provided that the free Pb2+ concentration in the incubation medium is kept below 0.1 mM by a heavy metal chelator. Under conditions suitable for Na+,K+-ATPase activity precipitation of final reaction product (lead phosphate) at the sarcolemma of cardiac muscle is abolished by 0.1-1mM ouabain. In contrast, reaction product deposition at the intramuscular part of the plasma membrane and at intracellular sites is not noticeably affected by the glycoside. These findings indicate either that the sarcolemma is the exclusive location of Na+,K+-ATPase in cardiac muscle or that the presence of the enzyme at other loci is masked by active Na+,K+-independent, ouabain resistant ATPases. Under conditions favoring adenylate cyclase activity, precipitation by Pb2+ of orthophosphate derived, with the help of added cyclic nucleotide phosphodiesterase and 5'-nucleotidase, from cyclic AMP formed from adenylyl imidodiphosphate (AMP-PNP) is seen after prolonged incubation in myocardial cells along the entire course of the plasma membrane and also at the transverse tubules and is particularly intense at the tight junction regions of the intercalated disks. Ouabain has no effect on these reactions. Reaction product deposition is also observed at the sarcolemma in red skeletal muscle and at the terminal cisternae of the sarcoplasmic reticulum in white skeletal muscle, where the reaction is intensified by adrenaline. Sarcoplasmic reticulum of cardiac and of red skeletal muscle exhibits only relatively weak staining attributable to cyclic AMP formation. These observations are in agreement with the results of tissue fractionation studies according to which the plasma membrane is the chief site of adenylate cyclase in heart and in red, but not white skeletal muscle.
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PMID:Cytochemical studies on sarcolemma: Na+, K+-adenosine triphosphatase and adenylate cyclase. 13 Jun 56

Sarcolemmal Ca++-ATPase, Mg++-ATPase, and (Na+-K+)-ATPase activities were increased in late stages of heart failure in myopathic hamsters (BIO 14.6) without any changes in the adenylate cyclase activity. On the other hand, these hamsters at early and moderate stages of heart failure showed depressions in mitochondrial calcium binding and uptake and microsomal calcium binding. Sarcolemmal (Na+-K+)-ATPase was decreased in failing hearts because of substrate lack, oxygen lack, and perfusion with Ca++-free, Na+-free, or K+-free medium. Both Mg++-ATPase and Ca++-ATPase activities of sarcolemma did not change on perfusing the hearts with substrate-free, hypoxic, Na+-free, or K+-free medium. Adenylate cyclase activity decreased on substrate-free or Ca++-free perfusion. Intracellular calcium overload produced by perfusing the hearts with medium containing calcium after Ca++-free perfusion was associated with decrease in all the sarcolemmal-bound enzyme activities. All types of failing hearts employed in this study showed a dramatic shift in the electrolyte composition. Failure of the cardiac muscle to generate contractile force on treatment with trypsin was associated with defects in the functions of sarcolemma, mitochondria, and sarcoplasmic reticulum, whereas such an effect on treatment with phospholipase C was limited to alterations in the activities of sarcolemma. The data suggest that abnormality at the level of sarcolemma plays an important role in the pathogenesis of heart dysfunction; however, the degree and direction of alterations in the sarcolemmal functions seem to be dependent upon the type of heart failure.
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PMID:Role of sarcolemmal changes in cardiac pathophysiology. 13 Jun 63

Different antiarrhythmic agents such as quinidine, procaine amide, and lodocaine at 1 mM concentrations were found to depress the ability of an isolated perfused rat heart to generate contractile force. Quinidine, but not procaine amide or lidocaine, decreased calcium uptake by both mitochondrial and microsomal fractions at different concentrations of calcium. The mitochondrial phosphorylation rate, respiratory control index, and state 3 oxygen consumption, but not ADP:O ratio and state 4 oxygen consumption, were depressed by only quinidine. None of these agents had any effect on myofibrillar Mg2+-ATPase or Ca2+-stimulated ATPase activities. On the other hand, sarcolemmal Mg2+-ATPase and Ca2+-ATPase activities, but not Na+-K+-ATPase activity, were increased by all these drugs. The sarcolemmal adenylate cyclase (EC 4.6.1.1) activity was decreased by quinidine only. These results suggest some similarities and differences in the sites of action of quinidine, procaine amide, and lidocaine within the myocardium.
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PMID:Subcellular and functional effects of quinidine, procaine amide, and lidocaine on rat myocardium. 13 Sep 65

We studied hearts from sham-operated and uninfected catheterized rabbits as well as from rabbits at early and late stages of cardiomyopathy and failure after 3 and 6 days of infection with Streptococcus viridans. No ultrastructural abnormalities or biochemical changes in membrane and myofibrillar activities were seen in 3-day uninfected hearts. In 6-day uninfected hearts there were decreased sarcolemmal M2+ ATPase, Na+-K+ ATPase, adenylate cyclase and calcium binding, microsomal calcium binding and uptake, and myofibrillar Ca2+-stimulated ATPase as well as increased mitochondrial calcium uptake. Slight ultrastructural changes also were apparent in 6-day uninfected hearts. At both early and late stages of infective cardiomyopathy and failure there were varying degrees of depression in sarcolemmal Mg2+ ATPase, Na+-K+ ATPase, adenylate cyclase and calcium binding, microsomal calcium binding, calcium uptake and basal ATPase, and myofibrillar Ca2+-stimulated ATPase activities. However, sarcolemmal Ca2+ ATPase and myofibrillar Mg2+ ATPase activities were decreased only after 6 days of infection. Mitochondrial calcium binding and uptake were increased in early stages but decreased in late stages of disease. Furthermore in infected hearts there were defects in mitrochondrial respiration and phosphorylation. Generalized severe myocardial cell damage involving myofibrils, mitochondria, and the sarcotubular system was seen only in late stages of infection. The results demonstrate impairment of different membrane and contractile protein functions as well as ultrastructural abnormalities in bacterial cardiomyopathic hearts which were absent or of lesser magnitude in hearts with only hypertrophy. The findings reported here suggest to use that there is an association between heart failure and changes in function of cellular components during bacterial infective cardiomyopathy.
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PMID:Abnormalities in heart membranes and myofibrils during bacterial infective cardiomyopathy in the rabbit. 13 11

The relationship of the mucosal enzyme systems Na+-K+-activated adenosine triphophatase (Na-K-ATPase) and adenylate cyclase and their associated intestinal transport processes was studied in the rat ileum. Two ileal loops were constructed in each anesthetized rat; one loop was inoculated with saline, the other loop with choleragen. Net transport of water and electrolytes was measured in vivo after which enzyme activity was measured in the mucosa of the perfused loops. All doses of choleragen between 5 and 150 mug decreased water movement as early as 3 1/2 h after inoculation. A linear relationship between the dose of choleragen and the level of net water and electrolyte secretion was observed when choleragen doses between 5 and 150 mug were incubated in ileal loops for 4 h. Adenylate cyclase activity was always increased in secreting intestinal loops, whereas Na-K-ATPase was unaffected by choleragen. In animals pretreated with methylprednisolone acetate, 3 mg/100 g per day for 3 days before loop inoculation, saline loops had enhanced mucosal Na-K-ATPase activity had increased net water and electrolyte absorption; choleragen-exposed loops had increased adenylate cyclase and Na-K-ATPase activities, and net absorption of water and electrolytes 4 h after inoculation. These effects of methylprednisolone acetate were still present 19 1/2 h after inoculation. When a single injection of methylprednisolone acetate was given 3 1/2 h after choleragen inoculation, both adenylate cyclase and Na-K-ATPase were activated, and net intestinal absorption of water and electrolytes was observed 19 1/2 h after inoculation. These results suggest that methylprednisolone can prevent and reverse the secretory effects of choleragen by selectively stimulating a coexisting absorptive process.
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PMID:Prevention and reversal of cholera enterotoxin-induced intestinal secretion by methylprednisolone induction of Na+-K+-ATPase. 13 58

1. The activities of some membrane-bound enzymes such as adenylate cyclase, Na+ + K+-stimulated adenosine triphosphatase (Na+ + K+-ATPase), Ca2+-stimulated ATPase and Mg2+-stimulated ATPase were examined in heart sarcolemmal fractions from control and cardiomyopathic hamsters at different stages of heart failure. 2. The basal adenylate cyclase activity in sarcolemma from cardiomyopathic animals with early, moderate and late stages of heart failure was not different from the control values whereas the sodium fluoride- and catecholamine-stimulated adenylate cyclase activities were depressed in cardiomyopathic sarcolemma at moderate and late stages. 3. The sarcolemmal Na+ + K+-ATPase activity was decreased and the non-specific phosphatase activity was increased at early, moderate and late stages of heart failure. 4. The sarcolemmal Ca2+-ATPase activity was decreased at moderate and late stages whereas the Mg2+-ATPase activity was decreased at the late stages of heart failure only. 5. A marked decrease was found in calcium binding by heart sarcolemma from cardiomyopathic hamsters at late stages of failure. 6. These results suggest that dramatic sarcolemmal changes are associated with heart failure, and support the view that membrane abnormalities play a crucial role in the development of myocardial dysfunction, cyclase, calcium binding, heart failure, heart membranes, sarcolemmal enzymes.
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PMID:Comparison of heart sarcolemmal enzyme activities in normal and cardiomyopathic (UM-X7.1) hamsters. 13 61


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