Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: KEGG:D06103 (Theophylline)
 2,023 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In an earlier study, theophylline was shown to antagonize the morphine-induced inhibition of electrically induced contractions of the longitudinal muscle-myenteric plexus preparation from the guinea pig ileum. In the present study, acetylcholine (ACh) released from the myenteric plexus was measured directly using a radioenzymatic assay. Theophylline antagonized the morphine-induced inhibiton of ACh release. A similar antagonism was also observed with caffeine and 3-isobutyl-l-methylxanthine (IBMX). All three methylxanthines also increased ACh release. The nonxanthine phosphodiesterase (PDE) inhibitors 4-(3-butoxy-4-methoxy)-2-imidazolidinone (Ro 20-1724) and l-ethyl-4-isopropylidenehydrazino-1 H-pyrozolo(3,4-b)-pyridine-5-carboxylate, ethylester, HCl (SQ 20,009) generally did not antagonize the morphine-induced inhibiton of ACh release. The PDE inhibitor SQ 20,009 but not Ro 20-1724, enhanced the release of ACh. Both high calcium concentration and the divalent cation ionophore A23187 antagonized the inhibitory action of morphine on ACh release. These observations suggest that alteration in calcium fluxes rather than the inhibiton of PDE mediate the methylxanthine-induced antagonism of morphine in this preparation.
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PMID:Interactions of methylxanthines, nonxanthine phosphodiesterase inhibitors, and calcium with morphine in the guinea pig myenteric plexus. 49 98

A simple chromatographic procedure was developed for the separation and determination of theophylline and hydroxyethyltheophylline. An aliquot of diluted syrup was pipetted into a chromatographic column containing a strong anion-exchange resin, which retains theophylline and allows the hydroxyethyl derivative to pass through it. Theophylline was subsequently eluted with 1 N HCl and determined by difference spectrophotometry at 284 nm; its derivative was determined at 272 nm.
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PMID:Separation and spectrophotometric determination of theophylline and hydroxyethyltheophylline in a pharmaceutical syrup. 64 77

1. Following intravenous administration of morphine.HCl a reduction in mean arterial blood pressure (MABP) was produced, quaternary morphine analogue was ineffective. 2. Theophylline and 8-phenyltheophylline administration reduced morphine-induced hypotension. 3. A2 adenosine receptor agonist caused an hypotension while A1 adenosine receptor agonist was ineffective. 4. L-NG-Mono-methylarginine administration reduced the hypotensive effect of exogenous A2 agonist while it was ineffective on morphine-induced hypotension. 5. Morphine-induced hypotension was increased by pretreatment with dipyridamole, whereas tetrabenazine abolished it. 6. The present study is consistent with previous reports on the central hypotensive action of morphine and propose a role for adenosine release in morphine-induced hypotension.
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PMID:Adenosine release in morphine-induced hypotension in rats. 159 28

Constant drug release was achieved from theophylline tablets coated with a multiporous membrane in an aqueous environment. The tablets were coated with an aqueous acrylic latex containing a dispersed pore-forming agent with pH-dependent solubility characteristics. The pore former, dibasic calcium phosphate, was insoluble in the latex but leached out rapidly in 0.1 M HCl. Theophylline was then released at a constant rate through the multiporous membrane. The drug release was a function of the level of the pore-forming agent and the membrane thickness, but independent of the pH of the dissolution medium and the degree of agitation.
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PMID:Theophylline tablets coated with aqueous latexes containing dispersed pore formers. 228 Mar 64

Ionic mechanisms of modulating action of serotonin on acetylcholine responses in identified and nonidentified neurons of Helix pomatia were studied using the voltage-clamp method. A 1-3 min exposure to serotonin (10(-5)-10(-4) mol/l) depressed DNa-type, DCl-type and HCl-type of responses to acetylcholine (10(-6)-10(-4) mol/l) without modification of the reversal potential of acetylcholine-induced current. Theophylline produced effects analogous to those of serotonin which evidences for the participation of intracellular processes connected with the cyclase system of cell in modulating the serotonin action on acetylcholine responses. Serotonin produced a shift of the reversal potential and an increase of acetylcholine-induced current in neurons whose acetylcholine responses were associated with changes in the membrane permeability for several kinds of ions. Serotonin inhibited the inward current phase when two-phase acetylcholine responses of DNa-HK-type were observed. Ionic mechanisms of the modulating action of serotonin on acetylcholine responses in tested neurons are discussed on the basis of the data obtained.
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PMID:[Ionic mechanisms of the modulating effect of serotonin on acetylcholine responses of neurons in the edible snail]. 245 11

Etintidine HCl is a potent H2-blocker. The effect of clinical doses of etintidine on the disposition of theophylline was investigated in 10 male volunteers. This was a double-blind, two-way crossover study. Each subject received etintidine (400 mg) or placebo twice a day with meals for 4 days on two occasions (separated by 4 days). On each occasion, the subjects were fasted overnight on Day 3 and were given an oral dose of theophylline elixir (5 mg/kg) 30 min following the administration of the morning dose of etintidine or placebo on Day 4. Blood samples were collected prior to and up to 24 h following the administration of theophylline. Plasma theophylline levels were analysed by HPLC. Theophylline was rapidly absorbed following oral administration of the theophylline elixir to both the placebo and etintidine treatment groups. Comparison of the pharmacokinetic parameters of theophylline between the etintidine and the placebo groups indicates that while etintidine did not significantly (p greater than 0.05) affect the apparent Cmax (11.1 vs 10.0 micrograms ml-1) and Tmax (1.7 vs 1.4 h) values of theophylline, etintidine significantly reduced the oral clearance (0.0200 vs 0.0564 l kg-1 h-1, p = 0.000006) and prolonged the elimination half-life (16.8 vs 6.0 h) of theophylline. The data indicate that etintidine, like cimetidine, extended the elimination of theophylline in humans.
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PMID:Etintidine-theophylline interaction study in humans. 289 45

A method for the determination of theophylline and promethazine in suppositories is proposed which allows the determination of both components in a single suppositorium. The ingredients were extracted by hot water and addition of a little bit of sulfuric acid. Theophylline is determined potentiometrically without separation of promethazine by titrating the acid which is set free after addition of silver nitrate. Promethazine is separated by ether in alkaline medium, reextracted in HCl (0,1 mol/l) and determined colorimetrically. The precision of both methods is good. The results of the determination in the suppositories are given.
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PMID:[Determination of aminophylline and promethazine in suppositories]. 403 38

Several methodological aspects concerning the measurement of thyroid-stimulating antibodies (TSAb) were examined using a 5000-g particulate fraction from human thyroid tissue. TSH displayed maximal stimulation at 32 C. An ATP-regenerating system had no influence at ATP concentrations greater than 0.67 mM. Theophylline did not influence cAMP concentrations in the incubation medium after stimulation with increasing dosages of TSH, suggesting the absence of active phosphodiesterases in the membrane preparations. Sera dialyzed against Tris-HCl were as suitable as immunoglobulin G preparations for determination of TSAb. One hundred and nineteen patients with ophthalmic Graves' disease, 42 of whom were hyperthyroid at the time of study, were investigated for TSH binding-inhibiting antibodies ( TBIAb ) and TSAb. In 76% of these patients, concordance between the presence and absence of both activities was found independent of whether they were untreated, treated, or in remission. When gradations of potency in the two systems were compared, linear regression revealed a correlation coefficient of 0.59. The coefficient correlation increased when TBIAb and TSAb were each determined in a single assay using identical thyroid membrane preparations. In four other patients, both TSAb and TBIAb were measured repeatedly during the course of the disease. In three patients, both activities were parallel, whereas in one patient, dissociation of the two activities was found. The data suggest the presence of antibodies with varying stimulating and binding-inhibiting properties. However, in hyperthyroidism of Graves' disease, both activities usually were present in similar quantities.
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PMID:Methodological aspects and clinical results of an assay for thyroid-stimulating antibodies: correlation with thyrotropin binding-inhibiting antibodies. 614 92

In this work we show the existence of cyclic AMP phosphodiesterase (EC 3.1.4.17) in human erythrocyte membranes and have clarified some properties of the enzyme. In human erythrocytes, about 23% of the total cyclic AMP phosphodiesterase activity is in a membrane-bound form. Although it could be solubilized with Triton X-100 in 5 mM Tris-HCl buffer (pH 8.0), it was not solubilized by a low or high concentration of salt. The enzyme seems to be localized in the cytoplasmic surface, since it is detected in sealed inside-out vesicles of human erythrocyte membranes, but not in intact human erythrocytes. The optimum pH was found to lie between 7.4 and 8.0, and Mg2+ was found to be necessary for its activity. Ca2+ and calmodulin could not stimulate the activity of this enzyme. Theophylline was a strong inhibitor, but cyclic GMP could not inhibit the enzymic hydrolysis of cyclic [32P]AMP and this membrane-bound enzyme therefore seems to be specific to cyclic AMP.
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PMID:Studies on adenosine 3',5'-monophosphate phosphodiesterase of human erythrocyte membranes. 625 88

This study investigated the effect of acute changes in blood gases and pH on theophylline kinetics. Groups of 6 conscious rabbits were exposed to air (control) or to a high CO2 and/or low O2 atmosphere for 570 minutes, or received 47 ml/kg of 0.3N HCl by gavage. Once blood gases or pH were stabilized, they received 2.5 mg/kg theophylline intravenously. Urine, blood samples, and cerebrospinal fluid were collected. Metabolic acidosis did not modify theophylline kinetics. Theophylline serum concentrations increased with hypercapnia (p less than 0.05), hypoxemia (p less than 0.01), and hypercapnia combined with hypoxemia (p less than 0.001), compared with those in control animals. These increases were related to a decrease in theophylline nonrenal clearance (Clnr). Thus, Clnr decreased from 1.52 +/- 0.05 ml/min/kg in control animals to 1.13 +/- 0.13 in hypercapnia (p less than 0.01), 1.09 +/- 0.09 in hypoxemia (p less than 0.001), and 1.02 +/- 0.02 in hypoxemia combined with hypercapnia (p less than 0.001). Theophylline protein binding was not affected by any of the experimental conditions. The ratio of central nervous system to serum theophylline concentration was increased by 16% (p less than 0.05) with hypercapnia combined with hypoxemia. It was concluded that both hypercapnia and/or hypoxemia decreased theophylline biotransformation. Such a decrease may be the cause of toxicity.
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PMID:Influence of hypercapnia and/or hypoxemia and metabolic acidosis on theophylline kinetics in the conscious rabbit. 672 Dec 73


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