Stimulation of ion transport by ascorbic acid through inhibition of 3′:5′-cyclic-AMP phosphodiesterase in the corneal epithelium and other tissues
| Autor: | M G Buck, JoséA. Zadunaisky |
|---|---|
| Rok vydání: | 1975 |
| Předmět: |
Time Factors
Phosphodiesterase Inhibitors Biophysics Caudate nucleus Biological Transport Active Stimulation Ascorbic Acid Biochemistry Epithelium Retina Cornea Chlorides Species Specificity Theophylline medicine Animals Ion transporter Corneal epithelium Rana catesbeiana Chemistry Myocardium Brain Phosphodiesterase Cell Biology 3' 5'-cyclic-AMP phosphodiesterase Ascorbic acid Molecular biology medicine.anatomical_structure Liver 3' 5'-Cyclic-AMP Phosphodiesterases Organ Specificity Rabbits medicine.drug |
| Zdroj: | Biochimica et Biophysica Acta (BBA) - Biomembranes. 389:251-260 |
| ISSN: | 0005-2736 |
| DOI: | 10.1016/0005-2736(75)90319-3 |
| Popis: | Ascorbic acid stimulates active transport of Cl − by the isolated intact corneas. The effect is not present in corneas previously stimulated by theophylline, an inhibitor of 3′: 5′-cyclic-AMP phosphodiesterase (EC 3.1.4.17), and vice versa, theophylline has no action after stimulation with ascorbic acid. This indicated inhibition of 3′: 5′-cyclic-AMP phosphodiesterase by ascorbic acid. Assay of phosphodiesterase using 3 H-labeled cyclid AMP of frog and rabbit corneal epithelial homogenates showed an inhibitory effect of ascorbic acid. Concentration of 5 mM produced 16% inhibition with 20 mM producing 46 %. This compares with 58 % inhibition by theophylline at 5 mM. Phosphodiesterase activity is mostly soluble in frog corneal epithelium but in rabbit 45 % is particulate. Soluble and particulate fractions are inhibited by ascorbate, but in rabbits greater inhibition (50 %) was observed in the particulate fraction than in the soluble fraction. Other tissues showed inhibition also: frog retina 12 %, rat brain (caudate nucleus) 48 %, rabbit brain 14 %, rabbit liver 16 %. It is concluded that ascorbate produces an increase in cyclic AMP content of corneal epithelium and other tissues by inhibition of 3′: 5′-cyclic-AMP phosphodiesterase. This action may be one of the main functions of the high ascorbic acid content of ocular tissues and explain some of the effects of high dosis of ascorbate in other systems. |
| Databáze: | OpenAIRE |
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