Acute unilateral ureteral distension inhibits glutamate-dependent spinal pelvic-urethra reflex potentiation via GABAergic neurotransmission in anesthetized rats

Kuo Jung Chen, Hsien Yu Peng, Chen Li Cheng, Cheng Hsu Chen, Jiuan Miaw Liao, Yu Cheng Ho, Jung Tong Liou, Kwong Chung Tung, Tien Huan Hsu, Tzer Bin Lin

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15 Citations (Scopus)

Abstract

The effects of an acute increase in intraureteral pressure (IUP) on pelvic-urethra reflex potentiation were examined in urethane-anesthetized rats by recording the external urethral sphincter electromyogram activities evoked by the pelvic afferent stimulation. Compared with a single action potential elicited by the test stimulation (TS; characterized by an intensity that evoked a constant reflex response without facilitation, 1/30 Hz, 1.03 ± 0.12 spikes/stimulation, n = 7), the repetitive stimulation [RS; identical stimulation intensity as the TS (1 Hz)] significantly induced spinal reflex potentiation (SRP; 16.90 ± 2.00 spikes/stimulation, P <0.01, n = 7). Such SRP was significantly attenuated by intrathecal 2,3-dihydroxy-6-nitro-7- sulfamoyl-benzo (F) quinoxaline [NBQX; a glutamatergic α-amino-3-hydroxy- 5-methyl-4-isoxazoleproprionat (AMPA) receptor antagonist] and D-2-amino-5-phosphonovalerate [APV; a glutamatergic N-methyl-D-aspartate (NMDA) antagonist; the spike number per stimulation: 11.0 ± 0.70 for NBQX, 1.01 ± 0.30 for APV, and 16.90 ± 2.0 for RS, respectively, n = 7, P <0.01]. Acute stepwise elevations of IUP gradually attenuated and eventually abolished the RS-induced SRP (16.80 ± 1.30, 17.00 ± 1.30, 16.30 ± 1.30, 10.50 ± 1.80, 8.80 ± 1.90, 3.50 ± 1.60, 0.80 ± 0.20, 0.70 ± 0.20, and 0.20 ± 0.10 spikes/stimulation at intraureteral pressure of 0, 2.5, 5, 7.5, 10, 12.5, 15, 17.5, and 20 cmH 2O, respectively, n = 7). Intrathecal NMDA (a glutamatergic NMDA receptor agonist) and bicuculline (a GABA receptor antagonist) both reversed the abolition of RS-induced SRP caused by unilateral ureteral distension (14.0 ± 4.04 and 8.00 ± 1.53 spikes/stimulation, respectively, n = 7, P <0.01). All the results suggested unilateral ureteral distension might compensatorily relax the urethra via GABAergic inhibition of NMDA-dependent SRP.

Original languageEnglish
JournalAmerican Journal of Physiology - Renal Physiology
Volume292
Issue number3
DOIs
Publication statusPublished - Mar 2007
Externally publishedYes

Keywords

  • Intraureteral pressure
  • N-methyl-D-aspartic acid
  • Spinal reflex potentiation
  • Unilateral ureteral obstruction

ASJC Scopus subject areas

  • Physiology

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