Saphenous nerve stimulation normalizes bladder underactivity induced by tibial nerve stimulation in cats

Abstract

This study in α-chloralose-anesthetized cats aimed at investigating the bladder responses to saphenous nerve stimulation (SNS). A urethral catheter was used to infuse the bladder with saline and to record changes in bladder pressure. With the bladder fully distended, SNS at 1-Hz frequency and an intensity slightly below the threshold (T) for inducing an observable motor response of the hindlimb muscles induced large amplitude (40–150 cmH2O) bladder contractions. Application of SNS (1 Hz, 2–4T) during cystometrograms (CMGs), when the bladder was slowly (1–3 ml/min) infused with saline, significantly (P < 0.05) increased the duration of the micturition contraction to >200% of the control without changing bladder capacity or contraction amplitude. Repeated application (1–8 times) of intense (4–8T intensity) 30-min tibial nerve stimulation (TNS) produced prolonged post-TNS inhibition that significantly (P < 0.01) increased bladder capacity to 135.9 ± 7.6% and decreased the contraction amplitude to 44.1 ± 16.5% of the pre-TNS control level. During the period of post-TNS inhibition, SNS (1 Hz, 2–4T) applied during CMGs completely restored the bladder capacity and the contraction amplitude to the pre-TNS control level and almost doubled the duration of the micturition contraction. These results indicate that SNS at 1 Hz can facilitate the normal micturition reflex and normalize the reflex when it is suppressed during post-TNS inhibition. This study provides an opportunity to develop a novel neuromodulation therapy for underactive bladder using SNS.