Stretch independent regulation of prostaglandin E2 production within the isolated guinea-pig lamina propria

Authors

  • Christopher J. Nile,

    1. The Uro-physiology Research Group, The Medical and Dental School, The University of Newcastle upon Tyne, Newcastle upon Tyne, UK, and
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  • Jan De Vente,

    1. European Graduate School of Neuroscience (EURON), The Department of Psychiatry and Neuropsychology, Maastricht University, Maastricht, The Netherlands
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  • James I. Gillespie

    Corresponding author
    1. The Uro-physiology Research Group, The Medical and Dental School, The University of Newcastle upon Tyne, Newcastle upon Tyne, UK, and
    2. European Graduate School of Neuroscience (EURON), The Department of Psychiatry and Neuropsychology, Maastricht University, Maastricht, The Netherlands
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James I. Gillespie, The Uro-physiology Research Group, The Medical and Dental School, The University, Newcastle upon Tyne, NE2 4BW, UK.
e-mail: j.i.gillespie@ncl.ac.uk

Abstract

OBJECTIVE

To use an isolated preparation of the guinea-pig bladder lamina propria (LP) to investigate the effects of adenosine tri-phosphate (ATP) and nitric oxide (NO) on the release of prostaglandin E2 (PGE2).

MATERIALS AND METHODS

The bladders of female guinea-pigs (200–400 g) were isolated and opened to expose the urothelial surface. The LP was dissected free of the underlying detrusor muscle and cut into strips from the dome to base. Strips were then incubated in Krebs buffer at 37 °C. Each tissue piece was then exposed to the stable ATP analogue, BzATP, and a NO donor, diethylamine-NONOate (DEANO), and the effect on PGE2 output into the supernatant determined using the ParameterTM PGE2 enzyme immunoassay kit (R & D Systems, Abingdon, UK). Experiments were repeated in the presence of purinergic receptor and cyclooxygenase (COX) enzymes, COX I and COX II, antagonists. The cellular location of COX I, COX II and neuronal NO synthase (nNOS) within the bladder LP was also determined by immunohistochemistry.

RESULTS

PGE2 production was significantly increased by BzATP. Antagonist studies showed the purinergic stimulation involved both P2X and P2Y receptors. The BzATP response was inhibited by the COX inhibitor indomethacin (COX I >COX II) but not by DUP 697 (COX II >COX I). Thus, BzATP stimulation occurs because of COX I stimulation. NO had no effect on PGE2 production over the initial 10 min of an exposure. However, PGE2 output was increased 100 min after exposure to the NO donor. In the presence of NO, the BzATP stimulation was abolished. Immunohistochemistry was used to confirm the location of COX I to the basal and inner intermediate urothelial layers and to cells within the diffuse layer of LP interstitial cells. In addition, nNOS was also located in the basal urothelial layers whilst COX II was found in the interstitial cell layers.

CONCLUSIONS

There is complex interaction between ATP and NO to modulate PGE2 release from the bladder LP in the un-stretched preparation. Such interactions suggest a complex interrelationship of signals derived from this region of the bladder wall. The importance of these interactions in relation to the physiology of the LP remains to be determined.

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