Int Neurourol J.  2017 Dec;21(4):259-269. 10.5213/inj.1734998.499.

Electrical Activity of the Bladder Is Attenuated by Intravesical Inhibition of P2X2/3 Receptors During Micturition in Female Rats

• Salazar BH
• Hoffman KA
• Zhang C
• Kavanagh A
• Zhang Y
• Boone TB
• Munoz A

• KMID: 2400893
• DOI: http://doi.org/10.5213/inj.1734998.499

Abstract

PURPOSE
To simultaneously monitor electrical discharges in various bladder regions and the external urethral sphincter (EUS) during voiding contractions, and to assess the functional role of myogenic modulation of the lower urinary tract (LUT) by ionotropic purinergic receptors containing the P2X3 subunit.
METHODS
Female Sprague-Dawley rats were anesthetized with urethane, and implanted with a suprapubic catheter for open cystometry. Flexible microelectrodes were placed ventrally in the bladder dome, upper bladder, lower bladder, and bladder base, along with the middle section of the exposed EUS. Intravesical P2X3-containing receptors were blocked with AF-323, a specific P2X3-P2X2/3 receptor antagonist. A digital electrophysiology amplifier was used to record electrical and cystometric signals throughout the LUT.
RESULTS
Electrical activity in the LUT started before effective voiding contractions. Bladder pressure and electrical waveforms showed consistent out-of-phase activity when compared with the recordings made at the EUS. This pattern was also observed during voiding contractions in the presence of AF-353, supporting the hypothesis that during bladder distension, activation of P2X3-containing receptors is required for voiding contractions. Furthermore, the inhibition of P2X3-containing receptors significantly decreased the amplitude of electrical signals in the urinary bladder, but not the base or EUS.
CONCLUSIONS
Our results provide novel information about the regulation of the micturition process by P2X3-containing receptors located in the inner layers of the bladder.

Keyword

Lower Urinary Tract Symptoms; Urination; Purinergic P2X Receptor Antagonists; Urinary Bladder; Electrophysiology

MeSH Terms

Animals
Catheters
Electrophysiology
Female*
Humans
Lower Urinary Tract Symptoms
Microelectrodes
Purinergic P2X Receptor Antagonists
Rats*
Rats, Sprague-Dawley
Receptors, Purinergic
Urethane
Urethra
Urinary Bladder*
Urinary Tract
Urination*
Purinergic P2X Receptor Antagonists
Receptors, Purinergic
Urethane