Recurrent inhibition in sacral parasympathetic pathways to the bladder

Abstract

SUMMARY1. The effects produced by stimulation of the central end of transected ventral roots were observed on spontaneous and evoked vesical contractions and on the firing of sacral parasympathetic neurones.2. Recurrent inhibition of sacral parasympathetic neurones was demonstrated at frequencies of stimulation above 10/sec and at intensities above threshold for the parasympathetic axons.3. Recurrent inhibition was present in chloralose cats, as well as in decerebrate animals and was unaffected by chronic spinal transection.4. Interneurones were located which are presumed to be the autonomic equivalents of the somatic Renshaw cells. They were synaptically activated by antidromic stimulation of preganglionic fibres in sacral ventral roots.5. The inhibition of vesical contractions and the firing of the interneurones was reduced when the intravesical pressure was raised.6. The recurrent inhibition was unaffected by the intravenous injection of dihydro-,8-erythroidine.7. Strychnine reduced the recurrent inhibition in some experiments but the results were inconsistent. The effects of picrotoxin were inconclusive. 8. The possible role of recurrent inhibition in micturition is discussed.

Inhibitory interactions between colonic and vesical afferents in the micturition reflex of the cat.

“…It may be argued that the studies in this paper involving the use of electrical stimulation of colonic branches of the pelvic nerve could have activated the recurrent inhibitory pathway described de Groat & Ryall (1968) and de Groat (1976). There are three arguments to suggest that this is not the mechanism of the inhibition described here: first, the inhibition can be produced by physiological distensions of the colon; secondly, the inhibition described is powerful and is effective at large 50 VESICO-COLONIC REFLEX INTERACTIONS bladder volumes, e.g.…”

“…In some experiments a small early wave (latency 15-20 msec) was also present. All the evoked waves were recorded when the bladder volume was high (pressures of at least 30 mmHg between contractions), because at pressures below this level, variations in the spino-bulbo-spinal component of the evoked potential could have been due to concomitant changes in bladder pressure (de Groat & Ryall, 1968;de Groat, 1975).…”

Urodynamic investigations in patients with spinal cord injury: should the ice water test follow or precede the standard filling cystometry?

“…15 This recurrent inhibition, which has been demonstrated to originate from axon collaterals of bladder preganglionic neurons, 16,17 is supposed to act at spinal interneurons prior to the preganglionic lower urinary tract (LUT) neurons. 15,18 The PMC in contrast induces the micturition reflex via one long descending pathway to the sacral spinal cord where the reflex is further mediated by segmental interneurons as an all-or-none response.…”

Ion channels of the mammalian urethra

“…The impulse/desire to urinate is thought to result from the high firing rate of afferent sensory nerves stimulated by mechanoreceptors in the bladder wall, which are activated by the rise in intravesicular pressure in the bladder. 3,4 These afferent sensory nerves project top the dorsal horn of the spinal cord via the pelvic nerve and connecting fibers then travel to higher brain regions (i.e., pontine micturition center and cerebrum 5 ). The urethra is located distal to the bladder neck and connects the bladder interior to the exterior environment (Fig.…”