The effects of exogenous prostaglandins and the identification of constitutive cyclooxygenase I and II immunoreactivity in the normal guinea pig bladder

• Published in: BJU international 2007-08, Vol.100 (2), p.419-429
• Main Authors: De Jongh, Rik, Van Koeveringe, Gommert A., Van Kerrebroeck, Philip E.V., Markerink‐van Ittersum, Marjanne, De Vente, Jan, Gillespie, James I.
• Format: Article
• Language: English
• Subjects: Animals; autonomous activity; Biological and medical sciences; bladder; Cyclooxygenase 1 - metabolism; Cyclooxygenase 2 - metabolism; cyclo‐oxygenase; Female; Guinea Pigs; Medical sciences; Nephrology. Urinary tract diseases; prostaglandins; Prostaglandins - pharmacology; Urinary Bladder - drug effects; Urinary Bladder - enzymology
• ISSN: 1464-4096; 1464-410X
• DOI: 10.1111/j.1464-410X.2007.07011.x

OBJECTIVES To establish the functional consequences of exposing the isolated whole bladder preparation to exogenous prostaglandins (PGE1, PGE2, PGF2α) and to determine which cells express cyclooxygenase (COX) types I and II, to generate PG to effect these changes in vivo. MATERIALS AND METHODS Fifteen female guinea pigs (270–350 g) were used, i.e. seven for structural studies and eight for physiological measurement. For the structural study pieces of the lateral wall were incubated separately in Krebs’ solution at 36 °C, gassed with 95% O2 and 5% CO2 with 1 mm isobutyl‐methyl‐xanthene. Individual pieces were then exposed to 100 µm of the nitric oxide (NO) donor NONOate for 10 min; control tissues remained in Krebs’ solution. Tissues were then fixed in 4% paraformaldehyde. For the physiological experiments bladders were isolated and a cannula inserted into the urethra to monitor intravesical pressure. The bladders were suspended in a chamber containing carboxygenated physiological solution at 33–36 °C. All drugs were added to the abluminal bladder surface. RESULTS In the resting bladder there were small spontaneous transient rises in pressure, i.e. autonomous activity. Exposure to PGE2 (3–300 nm) resulted in an increase in basal pressure on which were superimposed autonomous activity, which was increased both in amplitude and frequency. The changes in the amplitude and frequency depended on the concentration of PGE2. After a brief exposure (240 s) to PGE2 the augmentation of the autonomous activity continued for >60 min despite regular washing. The responses were similar with PGE1 but the responses to PGF2α and arachidonic acid were reduced. The augmented activity was reduced by the EP1/EP2 receptor blocking agent AH6809 (10 µm). Using an antibody to the 70 kDa constitutive form (COX I), COX I immunoreactivity (COX I‐IR) was located in cells in the basal urothelium, in lamina propria and cells on the surface of the inner muscle bundles. There were few COX I‐IR cells associated with the outer muscle bundles. The COX I‐IR cells lying within the lamina propria were distinct from the suburothelial cells which respond to NO with an increase in cGMP. The lamina propria COX I‐IR cells appeared to form a network surrounding muscle trabeculae within the inner muscle layer. COX II‐IR was associated with the nuclei of cells in the urothelium, lamina propria and muscle. CONCLUSIONS These data show that PGs regulate autonomous activity. Potential sources of endogenous P