Inhibitory Effects of Rolipram on Partially Purified Phosphodiesterase 4 From Rat Brains
| Autor: | Miki Yamauchi, Shoichi Murakami, Jun Baba, Aiko Sawa, Fukuichi Ohsawa, Hiroshi Nagaso |
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| Rok vydání: | 1998 |
| Předmět: |
Male
medicine.medical_specialty Phosphodiesterase Inhibitors Pharmacology Inhibitory postsynaptic potential Substrate Specificity Structure-Activity Relationship Phosphodiesterase-4 Stereospecificity Internal medicine medicine Animals Rats Wistar IC50 Rolipram Dose-Response Relationship Drug biology Chemistry Brain Phosphodiesterase Stereoisomerism Chromatography Ion Exchange Pyrrolidinones Enzyme assay Cyclic Nucleotide Phosphodiesterases Type 4 Rats Kinetics Endocrinology 3' 5'-Cyclic-AMP Phosphodiesterases biology.protein Enantiomer Subcellular Fractions medicine.drug |
| Zdroj: | Japanese Journal of Pharmacology. 77:147-154 |
| ISSN: | 0021-5198 |
| Popis: | Several previous studies have demonstrated that the phosphodiesterase 4 selective inhibitor rolipram affects cellular function at a much lower concentration than the reported Ki value for phosphodiesterase 4 inhibition. In this study, we examined the inhibitory effect of rolipram on rat brain phosphodiesterase 4 to determine the heterogeneity of the enzyme activity. Partial purification of various phosphodiesterases from the rat brain was performed by anion-exchange chromatography. The eluant was pooled into four fractions, two of which manifested cAMP-selective phosphodiesterase activity that was blocked by 10 μM of rolipram, indicating the presence of phosphodiesterase 4 in these fractions. The IC50 of rolipram (racemate) of these two fractions was 492 and 79 nM, respectively. The R-(—)-enantiomer of rolipram inhibited the cAMP-phosphodiesterase activity in the latter fraction 10 times more than did S-(+)-rolipram, and the inhibition of the former fraction was less stereospecific. Dixon plot analysis revealed that the rolipram enantiomers inhibited the cAMP-phosphodiesterase in the latter fraction in a multiphasic manner, with two Ki values, one at the micromolar level and the other at the sub-micromolar level, respectively, for both of the enantiomers. These results suggest that there is a heterogeneity for phosphodiesterase 4 in the rat brain, and some of the phosphodiesterase forms are sensitive to rolipram. |
| Databáze: | OpenAIRE |
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