Reflexes evoked by electrical stimulation of afferent axons in the pudendal nerve under empty and distended bladder conditions in urethane-anesthetized rats.
This study examined reflex mechanisms that mediate urinary bladder and external urethral sphincter (EUS) coordination in female Sprague-Dawley urethane-anesthetized rats under empty and distended bladder conditions. The bladder was distended either by a small balloon or a saline filled catheter inserted through the body of the bladder. Stimulation of the entire pudendal nerve elicited short latency (8-12 ms) responses in the EUS and short (3-8 ms) and long latency responses (16-20 ms) in contralateral pudendal nerve. The long latency pudendal-pudendal reflex was reduced by 36.7% in area during bladder distension with the balloon catheter. However, there was no significant change in the area of pudendal-EUS reflex during bladder distension. Peak amplitudes of both reflexes were reduced 32% by bladder distension. The effects of glutamatergic receptor antagonists on the reflexes were also examined. MK 801 (0.3-5mg/kg, i.v.), an N-methyl-d-aspartate glutamatergic receptor antagonist, markedly depressed the pudendal-pudendal reflex, but LY 215490 (3mg/kg, i.v.), an alpha-amino-5-methyl isoxazole-4-propionate antagonist, had a minimal inhibitory effect. Both glutamatergic receptor antagonists significantly suppressed the pudendal-EUS reflex. These results indicate that the EUS is innervated by multiple pathways and that glutamatergic excitatory transmission is important in the neural mechanisms underlying bladder-sphincter coordination in the rat.
Chang
Hui-Yi
HY
Institute of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan.
Cheng
Chen-Li
CL
Chen
Jia-Jin J
JJ
Peng
Chi-Wei
CW
de Groat
William C
WC
D018686:Anesthetics, Intravenous; D000818:Animals; D001369:Axons / Q000502:physiology*; D002404:Catheterization; D016291:Dizocilpine Maleate / Q000494:pharmacology; D004558:Electric Stimulation; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005260:Female; D007546:Isoquinolines / Q000494:pharmacology; D009475:Neurons, Afferent / Q000502:physiology* / Q000648:ultrastructure; D051381:Rats; D017207:Rats, Sprague-Dawley; D017470:Receptors, Glutamate / Q000502:physiology; D012018:Reflex / Q000187:drug effects / Q000502:physiology*; D013777:Tetrazoles / Q000494:pharmacology; D014520:Urethane; D014521:Urethra / Q000294:innervation* / Q000502:physiology; D001743:Urinary Bladder / Q000294:innervation* / Q000502:physiology
D018686:Anesthetics, Intravenous; D018691:Excitatory Amino Acid Antagonists; D007546:Isoquinolines; D017470:Receptors, Glutamate; D013777:Tetrazoles; D014520:Urethane; D016291:Dizocilpine Maleate; C082309:tezampanel