Distribution of phosphodiesterase type 5 (PDE5) in the lateral wall of the guinea pig urinary bladder
Correspondence: Mohammad S. Rahnama'i, Department of Urology, Maastricht University Medical Centre, P. Debeyelaan 25, Maastricht, PO Box 5800, 6202 AZ, The Netherlands.
- To study PDE5 localisation by visualising the product of phosphodiesterase type 5 (PDE5) inhibition, namely cGMP, to determine the site of action of inhibitors in the urinary bladder.
Materials and Methods
- Bladders of nine male guinea pigs were dissected and treated in wells containing 2 mL Krebs' solution and 1 μM of the specific PDE5 inhibitor vardenafil at 36 °C for 30 min.
- After stimulating tissues with 100 μM of the nitric oxide (NO) donor diethylamine-NONOate for 10 min, the tissues were snap-frozen and 9–10 μm sections were cut.
- Sections were examined for cGMP immunoreactivity and also stained for vimentin, a marker for interstitial cells and the neuromarkers protein gene product 9.5 (PGP9.5), synaptic vesicle protein 2 (SV2), neurofilament (NF) and calcitonin gene-related peptide (CGRP), using the two-step indirect immunohistochemistry technique.
- After PDE5 inhibition, cGMP was found to be present in the urothelium, suburothelial interstitial cells and endothelium of blood vessels.
- cGMP was not expressed in nerves positive for CGRP, NF and SV2, and was expressed only in very few efferent nerves positive for PGP9.5.
- Our data show that the possible sites of action of PDE5 inhibition in the bladder are the urothelium, suburothelial interstitial cells and blood vessels, rather than the bladder nerve fibres.