P2X3 knock-out mice reveal a major sensory role for urothelially released ATP.
The present study explores the possible involvement of a purinergic mechanism in mechanosensory transduction in the bladder using P2X(3) receptor knock-out (P2X(3)-/-) and wild-type control (P2X(3)+/+) mice. Immunohistochemistry revealed abundant nerve fibers in a suburothelial plexus in the mouse bladder that are immunoreactive to anti-P2X(3). P2X(3)-positive staining was completely absent in the subepithelial plexus of the P2X(3)-/- mice, whereas staining for calcitonin gene-related peptide and vanilloid receptor 1 receptors remained. Using a novel superfused mouse bladder-pelvic nerve preparation, we detected a release of ATP proportional to the extent of bladder distension in both P2X(3)+/+ and P2X(3)-/- mice, although P2X(3)-/- bladder had an increased capacity compared with that of the P2X(3)+/+ bladder. The activity of multifiber pelvic nerve afferents increased progressively during gradual bladder distension (at a rate of 0.1 ml/min). However, the bladder afferents from P2X(3)-/- mice showed an attenuated response to bladder distension. Mouse bladder afferents of P2X(3)+/+, but not P2X(3)-/-, were rapidly activated by intravesical injections of P2X agonists (ATP or alpha,beta-methylene ATP) and subsequently showed an augmented response to bladder distension. By contrast, P2X antagonists [2',3'-O-(2,4,6-trinitrophenyl)-ATP and pyridoxal 5-phosphate 6-azophenyl-2',4'-disulfonic acid] and capsaicin attenuated distension-induced discharges in bladder afferents. These data strongly suggest a major sensory role for urothelially released ATP acting via P2X(3) receptors on a subpopulation of pelvic afferent fibers.
Vlaskovska
M
M
Autonomic Neuroscience Institute, Royal Free and University College Medical School, London NW3 2PF, United Kingdom.
Kasakov
L
L
Rong
W
W
Bodin
P
P
Bardini
M
M
Cockayne
D A
DA
Ford
A P
AP
Burnstock
G
G
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives* / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D002211:Capsaicin / Q000494:pharmacology; D004106:Dilatation; D004594:Electrophysiology; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D008297:Male; D008465:Mechanoreceptors / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D009475:Neurons, Afferent / Q000145:classification / Q000187:drug effects / Q000502:physiology; D010388:Pelvis / Q000294:innervation; D010525:Peripheral Nerves / Q000187:drug effects / Q000502:physiology; D058910:Purinergic P2 Receptor Agonists; D058919:Purinergic P2 Receptor Antagonists; D011732:Pyridoxal Phosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D018048:Receptors, Purinergic P2 / Q000172:deficiency*; D058477:Receptors, Purinergic P2X3; D001743:Urinary Bladder / Q000187:drug effects / Q000294:innervation / Q000378:metabolism; D019459:Urothelium / Q000378:metabolism*
C009587:2',3'-O-(2,4,6-trinitrophenyl)adenosine 5'-triphosphate; C546409:P2rx3 protein, mouse; D058910:Purinergic P2 Receptor Agonists; D058919:Purinergic P2 Receptor Antagonists; D018048:Receptors, Purinergic P2; D058477:Receptors, Purinergic P2X3; C077792:pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid; D011732:Pyridoxal Phosphate; D000255:Adenosine Triphosphate; C002630:alpha,beta-methyleneadenosine 5'-triphosphate; D002211:Capsaicin