Distribution of P2X₁ and P2X₃ Receptors in the Rat and Human Urinary Bladder

Abstract

Adenosine 5′-triphosphate (ATP) is known to play a significant role as a neurotransmitter in smooth muscle. There is evidence to show that ATP can cause bladder contractions and may also be involved in the processing of sensory information in the urinary bladder. These effects are likely to be mediated by P2X receptors, namely P2X₁ and P2X₃, respectively. This study set out to investigate their distribution in rat and human urinary bladders. P2X₁ receptor immunoreactivity was found on detrusor muscle fibres and P2X₃ receptor immunoreactivity was found in the urothelium of both species. This is the first demonstration of a non-neuronal localisation for P2X₃ receptors. No clear evidence was found for the presence of P2X₃ receptors on calcitonin gene-related peptide-containing sensory nerves and therefore P2X₃ receptors may not have a direct role in the mediation of sensory responses to ATP in the urinary bladder.

ATP and purinergic receptor–dependent membrane traffic in bladder umbrella cells

“…The pharmacological data presented above support the involvement of P2X receptors in regulating membrane exocytosis but are complicated by a lack of specific agonists/antagonists for individual P2X receptor subunits. In the present study, we observed P2X 3 localization along focal regions of the basolateral surface of rabbit umbrella cells and the plasma membrane of underlying cell layers ( Figure 5, A and B), which is consistent with previous reports of P2X 3 expression in the uroepithelium (16,25). No staining was observed when antigenic peptide was included in the reactions (data not shown).…”

“…For example, P2X 1 receptors are found on the detrusor smooth muscle (15,16), and there is evidence that ATP may regulate bladder contractility (17)(18)(19)(20). Furthermore, receptors containing the P2X 3 receptor subunit are found on pelvic afferent nerves that innervate the urinary bladder (20) and may function to sense bladder filling and storage (20,21).…”

“…The bladder epithelium releases ATP in response to mechanical stimuli (20,22), and it is hypothesized that ATP released from the serosal surface of the uroepithelium during bladder filling stimulates P2X 3 -containing receptors on suburothelial sensory nerve fibers, thus signaling information about urinary bladder filling (21). The uroepithelium also expresses multiple purinergic receptors, including all 7 P2X receptor subunits as well as P2Y 1 , P2Y 2 , and P2Y 4 receptors (15)(16)(17)(23)(24)(25). However, the nature of the functional receptors and their role in this tissue remain unknown.…”

Botulinumtoxin in der Urologie

“…Doch auch das Urothel selbst zeigt eine vielgestaltige Mitwirkung in der Blasenfüllungs-und -entleerungsfunktion: es exprimiert TRPV1-und P2X3-positive Rezeptoren (Apostolidis et al, 2005a;Elneil et al, 2001;Lazzeri et al, 2004) und antwortet auf Distension hin mit der…”

“…So konnten verschiedene Arbeitsgruppen erhöhte urotheliale TRPV1-Levels bei neurogener DO feststellen (Apostolidis et al, 2005a;Elneil et al, 2001;Lazzeri et al, 2004). Patienten, die auf Resiniferatoxin gut ansprachen, zeigten postinterventionell eine entsprechend ausgeprägte Reduktion dieser Levels, und parallel dazu eine Reduktion auch der suburothelialen TRPV1 exprimierenden Afferenzen (Apostolidis et al, 2005a;Apostolidis et al, 2005b).…”