title: The cGMP-binding, cGMP-specific phosphodiesterase (PDE5): intestinal cell expression, regulation and role in fluid secretion.
abstract: The expression and regulation of the cGMP-binding, cGMP-specific phosphodiesterase, PDE5, was studied in intestinal cells. Both PDE5A1 and PDE5A2 splice forms were cloned from the cDNA prepared from human colonic T84 cells, and PDE5 activity was dependent on increases in intracellular cGMP levels which correlated with increased phosphorylation of the enzyme. PDE5 expression was monitored in different regions of the gastrointestinal tract and nearly 50% of the phosphodiesterase activity in the duodenum, jejunum, ileum and colon was inhibited by sildenafil citrate. Administration of the stable toxin to intestinal loops resulted in activation of PDE5. Inhibition of PDE5 by sildenafil citrate led to fluid accumulation in loops, suggesting a possible explanation for the side effect of diarrhoea observed in individuals administered sildenafil citrate. Our results therefore represent the first study on the expression and regulation of PDE5 in intestinal tissue, and indicate that mechanisms to control its activity may have important consequences in intestinal physiology.
authors.affiliation: Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Malleswaram, Bangalore 560012, India.
authors.forename: Shailaja
authors.initials: S
authors.lastname: Sopory
authors.forename: Tanvir
authors.initials: T
authors.lastname: Kaur
authors.forename: Sandhya S
authors.initials: SS
authors.lastname: Visweswariah
mesh_terms: D015106:3',5'-Cyclic-GMP Phosphodiesterases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000818:Animals; D002458:Cell Fractionation; D002478:Cells, Cultured; D003001:Cloning, Molecular; D006152:Cyclic GMP / Q000378:metabolism*; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D007422:Intestines; D010766:Phosphorylation / Q000187:drug effects; D010879:Piperazines / Q000494:pharmacology; D019154:Protein Splicing / Q000235:genetics*; D011687:Purines; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000502:physiology; D000068677:Sildenafil Citrate; D013450:Sulfones
chemical_list: D010879:Piperazines; D011687:Purines; D013450:Sulfones; D000068677:Sildenafil Citrate; D015106:3',5'-Cyclic-GMP Phosphodiesterases; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5; C517381:PDE5A protein, human; C517384:Pde5a protein, rat; D006152:Cyclic GMP