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

The effects of 1-hexyl-3,7-dimethyl-xanthine (pentifylline, Cosaldon) and theophylline on rat brain Na+-, K+-, Mg2+ ATPase activities were investigated in in vitro experiments. It was established that pentifylline inhibits catecholamine sensitive ATPase in a dose dependent manner. Theophylline was without effect. Pentifylline also inhibited the Mg2+-dependent portion of Na+, K+-, Mg2+-ATPase. The effect of pentifylline on the kinetic parameters of Na+-, K+-, Mg2+-ATPase of synaptosomes was studied in detail. It was shown by a Lineweaver-Burk plot under the influence of pentifylline that the Michaelis constant (Km) increases from 1.0 x 10(-4) mol/l to 6.7 x 10(-4) mol/l. Km by norepinephrine stimulated ATPase decreases from 3.7 x 10(-4) mol/l to 2.9 x 10(-4) mol/l. In both experimental situations a decrease of maximal reaction velocity (Vmax) was observed. At high concentration of potassium in incubation medium the ATPase of synaptosomes was significantly more sensitive to pentifylline than at low concentration of potassium. The inhibition of ATPase by pentifylline was not influenced by the change in Na+/K+ ratio in the incubation medium. In all these experiments, theophylline used as a standard xanthine, was virtually without effect on the reaction kinetic of Na+-, K+-ATPase.
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PMID:[The influence of pentifylline and theophylline on reaction kinetics on rat brain ATPase stimulatable by catecholamines (author's transl)]. 22 24

Interactions between some substances (theophylline, noradrenaline, imidazole, ouabain and verapamil) and adenosine or adenosine triphosphate (ATP) were examined by recording the twitch tension of partially magnesium blocked phrenic-rat diaphragm preparations stimulated indirectly. Theophylline (an inhibitor of phosphodieterases) prevented and reversed the neuromuscular depression induced either by adenosine or ATP, and these substances antagonized the neuromuscular facilitation caused by imidazole (an activator of phosphodiesterases); noradrenaline and ouabain did not modify and verapamil increased that depression. These results indicate that the putative purine presynaptic receptor is not the ATPase, that it does not appear to operate by implication of cyclic AMP, but that it could mediate a process involved in the reduction of transmitter release by regulating the entry of calcium that follows the depolorization of the motor nerve endings.
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PMID:Purine effects at the neuromuscular junction and their modification by theophylline, imidazole and verapamil. 47 9

Stimulation by serum of cell proliferation in G1-arrested culture of Chinese hamster ovary cells CHO-K1 was accompanied by an early (during the first minutes) and delayed (2-10 h) activation of Na+,K+-ATPase and an increase in cell K+ content from 0.5-0.6 to 0.7-0.8 mmol per gram protein. Isoproterenol acted synergistically with serum in eliciting both early and delayed changes in K+ transport and in stimulating G1----S transition. Isoproterenol alone (without serum) induced a transient increase in K+ influx via Na+,K+-ATPase without changing the cell K+ content or having any mitogenic effect. Theophylline enhanced the serum-induced early activation of Na+,K+-ATPase but inhibited both the delayed increase in cell K+ and the G1----S transition. Early serum-induced increase in K+ transport was not affected by cycloheximide, whereas net accumulation of cell K+ was abolished by the drug. It is concluded that the early and the delayed activation of Na+,K+-ATPase induced by mitogens can be dissociated; the early ionic response is related to the primary transduction of membrane signal, whereas the delayed modulation of ion transport via Na+,K+-ATPase has another function and is associated with cell growth.
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PMID:Early and delayed changes in potassium transport during the initiation of cell proliferation in CHO culture. 254 16

The in vitro action of SP and theophylline on the activities of (Na K) and (Ca Mg) dependent adenosine-5'-triphosphates (ATPase) of crude synaptosomal membranes (SM) of four different areas of rat brain was investigated. The highest activity of (Ca Mg)ATPase was observed in SM from hippocampus. In thalamus with hypothalamus region the highest activity of (Na K)ATPase and the lowest activity of (Ca Mg)ATPase occurred. It was found, that 10 mumol of SP stimulating "alternatively" both (Na K) and (Ca Mg)ATPase activities from different regions may constitute a regulating agent for ionic transport in CNS of rat. Theophylline on concentration of 5 mumol modulates the action of SP on the activities of the investigated enzymes.
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PMID:Role of theophylline during the action of SP in vitro on the activity of synaptosomal membrane ATPase (EC 3.6.1.3) from different areas of rat brain. 258 49

In electrically stimulated rabbit ventricular strips, theophylline (0.3-30 mM) antagonized the increased contractility produced by ouabain (0.8 microM). Initial velocity of specific [3H]ouabain binding to homogenates prepared from the muscle strips was used to determine the fraction of binding sites occupied by ouabain. Theophylline decreased the binding of ouabain to (Na+ + K+)-ATPase. It is concluded that the effect of theophylline on ouabain-induced positive inotropism may be mediated by decreased ouabain binding to (Na+ + K+)-ATPase.
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PMID:Interaction between theophylline and ouabain in the rabbit heart: effect on (Na+ + K+)-ATPase. 300 8

1. We have previously shown that salbutamol induced hypokalaemia, like adrenaline induced hypokalaemia, is the result of stimulation of a membrane bound beta 2-adrenoreceptor linked to Na+/K+ ATPase. We have also demonstrated that adrenaline induced hypokalaemia is potentiated by therapeutic concentrations of theophylline. 2. In a single-blind study of 14 normal volunteers, we infused salbutamol in doses used in clinical practice and examined the effects of the addition of theophylline alone or combined with (-)-adrenaline on plasma potassium levels, heart rate and blood pressure. The combinations studied were (i) salbutamol + vehicle control adrenaline infusion + placebo theophylline; (ii) salbutamol + vehicle control adrenaline infusion + theophylline; (iii) salbutamol + adrenaline + theophylline. 3. In a randomised, balanced placebo controlled design oral slow release theophylline or placebo was given for 9 days. Subjects were studied twice on the active limb (days 7 and 9) and once on the placebo limb (day 9) and the procedure was identical on each of the 3 study days except for the solutions administered. 4. Theophylline increased salbutamol induced hypokalaemia and in some individuals profound hypokalaemia (less than 2.5 mmol l-1) was observed with these relatively low doses of salbutamol and theophylline. Adrenaline did not further increase the magnitude of the fall in potassium observed. Combining theophylline with salbutamol increased the tachycardia resulting from the salbutamol infusion. Salbutamol infusion caused a fall in diastolic and rise in systolic blood pressure on all 3 study days and this was not altered by either theophylline or adrenaline alone or together.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Salbutamol induced hypokalaemia: the effect of theophylline alone and in combination with adrenaline. 340 37

Previous studies have documented decreased levels of platelet sodium, potassium adenosine triphosphatase (Na+, K+ ATPase) enzyme activity in allergic subjects. The purpose of this study was to determine the effect of several drugs used to treat allergy and asthma on platelet Na+,K+ ATPase activity. Platelets from five allergic and five nonallergic subjects were incubated at 37 degrees C for 30 minutes with cortisol (1.0 to 3.6 micrograms/ml), theophylline (10 to 40 micrograms/ml), cromolyn (0.5 to 2.0 micrograms/ml), albuterol (3 to 24 ng/ml), chlorpheniramine (2.5 to 20 micrograms/ml), or diluent. The platelets were then rinsed, sonicated, serially centrifuged, and assayed for Na+,K+ ATPase activity nmol/min x micrograms protein by spectrophotometry. Mean activity (+/- 1 SEM) for the diluent incubation was 5.55 +/- 1.27 nmol/min x micrograms protein and 0.91 +/- 0.32 nmol/min x micrograms protein for the nonallergic and allergic subjects, respectively. The enzyme activity of allergic platelets (same units as above) increased after incubation with the following drugs: cortisol, 6.07 +/- 1.75 (p < 0.025) at 1.0 micrograms/ml, 7.55 +/- 1.36 (p < 0.005) at 1.4 micrograms/ml, and 5.95 +/- 0.91 (p < 0.025) at 1.8 micrograms/ml; cromolyn, 5.79 +/- 1.68 (p < 0.050) at 1.0 micrograms/ml; and albuterol, 4.43 +/- 1.61 (p < 0.05) at 12 ng/ml. Theophylline and chlorpheniramine did not have a similar effect on Na+,K+ ATPase activity. These data show that some of the drugs commonly used to treat allergic patients, especially anti-inflammatory agents, can increase the depressed platelet levels of Na+,K+ ATPase activity observed in allergic subjects. Modulation of Na+,K+ ATPase is a possible mechanism of action for these drugs in vivo.
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PMID:In vitro modulation of platelet sodium, potassium adenosine triphosphatase enzyme activity by antiallergy drugs. 839 60