Isobutyl-1-methylxanthine

In contrast to the different types of receptor antagonists, omeprazole, the first HVK -ATPase inhibitor used clinically, causes a comparable inhibition of stimulated gastric acid secretion irrespective of the kind of stimulation Figure 4.3). Acid secretion can be induced in the rat perfused stomach-lumen model by an initial injection of isobutyl-methylxanthine (IBMX, a phosphodiesterase inhibitor) followed by an infusion of forskolin (direct stimulation of adenylate cyclase). This kind of stimulation represents an... 

Isobutyl-l-methylxanthine (3-isobutyl-l-methylpurine-2,6-dione) [28822-58-4] M 222.3, m 199-210°, 202-203°, pK ,t 6.7 (acidic NH). Recrystd from aqueous EtOH. 

Ia+ Murine class II major histocompatibility complex antigen IB4 Anti-CD 18 monoclonal antibody IBD Inflammatory bowel disease IBMX 3-isobutyl-l-methylxanthine IBS Inflammatory bowel syndrome iC3 Inactivated C3 iC4 Inactivated C4 IC50 Concentration producing 50% inhibition... 

De Mello WC Effect of isoproterenol and 3-isobutyl-1-methylxanthine on the junctional conductance in heart cell pairs. Biochim Biophys Acta 1989 1012 291-298. 

Isobutyl-1 -methylxanthine Methyl methacrylate Mono-A-methylacetoacetamide Methyl magnesium carbonate A-Monomethylformamide Methyl mercuric hydroxide... 

Least et al. reduced the sample size to 20 pi serum, plasma, or saliva, in a microscale procedure. The extraction was carried out with a chloroform-isopropanol solution of the internal standard, 3-isobutyl-l-methylxanthine. After alkylation with tetramethylammonium hydroxide and pentyl iodide, gas chromatography was carried out on a packed 3 OV-17 on Gas Chrom Q column, by temperature programming from 180°C to 260°C, and using a nitrogen sensitive detector. With the sample volume used, the background interference is equivalent to about 0.1 mg/litre, and 0.5 mg theophylline per litre can easily be measured. Between-run... 

To improve the theophylline analysis, Bailey et al. used 3-isobutyl-l-methylxanthine as... 

PENTYL DERIVATIVES OF THEOPHYLLINE (1), THEOBROMINE (2), 3-ISOBUTYL-1-METHYLXANTHINE (3) AND PHENOBARBITAL (4)28... 

Schwertner et al. introduced a salting-out procedure, in combination with single extraction using chloroform-isopropanol (95 5). 100 pi plasma samples could be effectively extracted with 2 ml chloroform-isopropanol. Theophylline was derivatized with pentafluoroben-zyl chloride, and 3-isobutyl-l-methylxanthine was used as an internal standard. This standard is similar to theophylline in extractability, derivatization rates, stability and chromatographic properties. Accurate measurements of plasma concentrations ( + 0.22 ug/ml) could be obtained with little or no interference from theophylline metabolites and other coextract-able material. A packed column with 3 OV-17 on Gas Chrom Q and temperature programming from 150°C to 250°C was used in combination with an electron capture detector. 

Huai, Q., Wang, H., Zhang, W., Colman, R.W., Robinson, H., and Ke, H. (2004) Crystal structure of phosphodiesterase 9 shows orientation variation of inhibitor 3-isobutyl-1-methylxanthine binding. Proc. Natl. Acad. Sci. U.S.A. 101, 9624-9. 

Huai, Q., Liu, Y., Francis, S.H., Corbin, J.D., and Ke, H. (2004) Crystal structures of phosphodiesterases 4 and 5 in complex with inhibitor 3-isobutyl-1-methylxanthine suggest a conformation determinant of inhibitor selectivity. J. Biol. Chem. 279, 13095-101. 

Solutions of drugs were prepared in 145 mM aqueous NaCl, from which a dose series was prepared. dl-Octopamine, dl-synephrine, dopamine, tolazoline, clonidine, yohimbine, cyproheptadine, gramine, chlorpromazine, promethazine, propranolol, metoclopramide, and 3-isobutyl-l-methylxanthine were obtained from Sigma Chemical Co. naphazoline from Aldrich Chemical Co. chlordimeform and phentolamine from Ciba Geigy mianserin from Research Biochemicals Inc. and lofexidine, XAMI, and tramazoline were gifts from Dr. R. Hollingworth, Purdue Univ. 

One of the proposed mechanisms by which OA exerts its regulatory actions is via an adenylate cyclase (12-18). In a preliminary test male CL were treated with the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX), alone and with OA. The dose of OA (10 ug/g) was one that induced little or no effect on male sensitivity (see Figure 1). Results showed that when treated with IBMX alone (10 Ug/g) male response to a low dosage of pheromone (0.01 mg) was not significantly enhanced over that observed with controls, or OA alone (20 vs. 15% source contacts respectively). However, when treated with 10 Ug/g OA and 10 Ug/g IBMX, 78% of the males successfully reached the source. IBMX clearly potentiated the effect of a low dose of OA on male sensitivity to pheromone ... 

At a screening concentration of 1.0 mM, none of these compounds gave noteworthy inhibition. The known phosphodiesterase inhibitors theophylline, isobutyl-3-methylxanthine (IBMX), and papaverine caused considerable inhibition at 1 mM and had IC50 values between 0.1 and 1.0 mM. It therefore seems unlikely that the excitatory effects caused by these octopaminergic agonists in invertebrates can be related to inhibition of cAMP phosphodiesterase activity. 

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