Selective blockade of phosphodiesterase types 2, 5 and 9 results in cyclic 3'5' guanosine monophosphate accumulation in retinal pigment epithelium cells.
OBJECTIVE
To investigate which phosphodiesterase (PDE) is involved in regulating cyclic 3'5' guanosine monophosphate breakdown in retinal pigment epithelium (RPE) cells.


METHODS
cGMP content in the cultured RPE cells (D407 cell line) was evaluated by immunocytochemistry in the presence of non-selective or isoform-selective PDE inhibitors in combination with the particulate guanylyl cyclase stimulator atrial natriuretic peptide (ANP) or the soluble guanylyl cyclase stimulator sodium nitroprusside (SNP). mRNA expression of PDE2, PDE5 and PDE9 was studied in cultured human RPE cells and rat RPE cell layers using non-radioactive in situ hybridisation.


RESULTS
In the absence of PDE inhibitors, cGMP levels in cultured RPE cells are very low. cGMP accumulation was readily detected in cultured human RPE cells after incubation with Bay60-7550 as a selective PDE2 inhibitor, sildenafil as a selective PDE5 inhibitor or Sch51866 as a selective PDE9 inhibitor. In the presence of PDE inhibition, cGMP content increased markedly after stimulation of the particulate guanylyl cyclase. mRNA of PDE2,PDE5 and PDE9 was detected in all cultured human RPE cells and also in rat RPE cell layers.


CONCLUSIONS
PDE2, PDE5 and PDE9 have a role in cGMP metabolism in RPE cells.
Diederen
R M H
RM
Department of Psychiatry and Neuropsychology, European Graduate School of Neuroscience, University of Maastricht, Maastricht, The Netherlands. r.diederen@NP.unimaas.nl
La Heij
E C
EC
Markerink-van Ittersum
M
M
Kijlstra
A
A
Hendrikse
F
F
de Vente
J
J
D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology; D015106:3',5'-Cyclic-GMP Phosphodiesterases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology; D000818:Animals; D002478:Cells, Cultured; D006152:Cyclic GMP / Q000378:metabolism*; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5; D005092:Exonucleases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology; D015870:Gene Expression; D006801:Humans; D017403:In Situ Hybridization; D008297:Male; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology*; D010727:Phosphoric Diester Hydrolases / Q000235:genetics / Q000502:physiology*; D010857:Pigment Epithelium of Eye / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D011917:Rats, Inbred Lew; D012160:Retina / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*
D010726:Phosphodiesterase Inhibitors; D012333:RNA, Messenger; D005092:Exonucleases; C022650:spleen exonuclease; D010727:Phosphoric Diester Hydrolases; D015105:3',5'-Cyclic-AMP Phosphodiesterases; C481508:Pde9a protein, rat; D015106:3',5'-Cyclic-GMP Phosphodiesterases; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5; C517381:PDE5A protein, human; C517384:Pde5a protein, rat; D006152:Cyclic GMP