Biomaterial Database

Mechanosensitive properties of pelvic nerve afferent fibers innervating the urinary bladder of the rat. 1994

J N Sengupta, and G F Gebhart

University of Iowa, College of Medicine, Department of Pharmacology, Iowa City 52242.

1. Single-unit activity was recorded from S1 dorsal root afferent fibers in pentobarbital-anesthetized rats. In 25 experiments, 245 afferent fibers were identified by electrical stimulation of the pelvic nerve. Fifty-two percent were C fibers (conduction velocity: 1.70 +/- 0.04 m/s; mean +/- SE) and 48% were A delta-fibers (conduction velocity: 11.07 +/- 0.95 m/s). 2. Of 245 pelvic nerve afferent fibers, 92 (38%) responded to noxious urinary bladder distension (UBD; 80 mmHg); 57 of these fibers were C fibers and 35 were A delta-fibers. Forty-four fibers responded to colorectal distension (CRD; 80 mmHg); 32 were C fibers and 12 were A delta-fibers. A total of 39 fibers were identified in the anal mucosa; 3 were C fibers and 36 were A delta-fibers. Seventy fibers (28%) in these experiments were unresponsive to either UBD or CRD or to probing of the anal mucosa; 32 were unmyelinated C fibers and 38 were A delta-fibers. 3. Reproducibility of responses to repeated UBD (80 mmHg, 20 s; 8 trials at 4-min intervals) was tested in 10 fibers. In nine fibers, responses to repeated distension did not change; one fiber exhibited a progressive decrease in response magnitude after the third trial. 4. Of the 92 afferent fibers that responded to UBD, 45 were further characterized for responses to graded intensities of UBD. Forty fibers had some resting activity (1.7 +/- 0.3 impulses/s) and five fibers exhibited no ongoing activity. The response to UBD adapted slowly during the 20-s period of phasic UBD or during slow isotonic filling of the bladder. 5. The stimulus-response function (SRF) of fibers (n = 45) to graded UBD was monotonic < or = 80 mmHg. Thresholds for responses were determined after extrapolation of the least-squares linear regression line to the ordinate, and varied between 0 and 45 mmHg. The frequency distribution profile of thresholds revealed two populations of pelvic nerve afferent fibers in the urinary bladder: a larger group (n = 36) of low-threshold (LT) fibers (5.7 +/- 1.0 mmHg) and a smaller group (n = 9) of high-threshold (HT) fibers (34 +/- 2.5 mmHg). 6. Responses of four LT fibers to graded UBD were tested before and 30 min after instillation of 0.5 ml of 0.5% acetic acid (pH 3) into the bladder. The mean threshold for response of these fibers before instillation of acetic acid (9.4 +/- 3.1 mmHg) more than doubled (to 22.3 +/- 6.7 mmHg) after instillation of acetic acid.(ABSTRACT TRUNCATED AT 400 WORDS)

UI	MeSH Term	Description	Entries
D008297	Male		Males
D008465	Mechanoreceptors	Cells specialized to transduce mechanical stimuli and relay that information centrally in the nervous system. Mechanoreceptor cells include the INNER EAR hair cells, which mediate hearing and balance, and the various somatosensory receptors, often with non-neural accessory structures.	Golgi Tendon Organ,Golgi Tendon Organs,Krause's End Bulb,Krause's End Bulbs,Mechanoreceptor,Mechanoreceptor Cell,Meissner's Corpuscle,Neurotendinous Spindle,Neurotendinous Spindles,Receptors, Stretch,Ruffini's Corpuscle,Ruffini's Corpuscles,Stretch Receptor,Stretch Receptors,Mechanoreceptor Cells,Bulb, Krause's End,Bulbs, Krause's End,Cell, Mechanoreceptor,Cells, Mechanoreceptor,Corpuscle, Meissner's,Corpuscle, Ruffini's,Corpuscles, Ruffini's,End Bulb, Krause's,End Bulbs, Krause's,Krause End Bulb,Krause End Bulbs,Krauses End Bulb,Krauses End Bulbs,Meissner Corpuscle,Meissners Corpuscle,Organ, Golgi Tendon,Organs, Golgi Tendon,Receptor, Stretch,Ruffini Corpuscle,Ruffini Corpuscles,Ruffinis Corpuscle,Ruffinis Corpuscles,Spindle, Neurotendinous,Spindles, Neurotendinous,Tendon Organ, Golgi,Tendon Organs, Golgi
D009412	Nerve Fibers	Slender processes of NEURONS, including the AXONS and their glial envelopes (MYELIN SHEATH). Nerve fibers conduct nerve impulses to and from the CENTRAL NERVOUS SYSTEM.	Cerebellar Mossy Fibers,Mossy Fibers, Cerebellar,Cerebellar Mossy Fiber,Mossy Fiber, Cerebellar,Nerve Fiber
D009435	Synaptic Transmission	The communication from a NEURON to a target (neuron, muscle, or secretory cell) across a SYNAPSE. In chemical synaptic transmission, the presynaptic neuron releases a NEUROTRANSMITTER that diffuses across the synaptic cleft and binds to specific synaptic receptors, activating them. The activated receptors modulate specific ion channels and/or second-messenger systems in the postsynaptic cell. In electrical synaptic transmission, electrical signals are communicated as an ionic current flow across ELECTRICAL SYNAPSES.	Neural Transmission,Neurotransmission,Transmission, Neural,Transmission, Synaptic
D009619	Nociceptors	Peripheral AFFERENT NEURONS which are sensitive to injuries or pain, usually caused by extreme thermal exposures, mechanical forces, or other noxious stimuli. Their cell bodies reside in the DORSAL ROOT GANGLIA. Their peripheral terminals (NERVE ENDINGS) innervate target tissues and transduce noxious stimuli via axons to the CENTRAL NERVOUS SYSTEM.	Pain Receptors,Receptors, Pain,Nociceptive Neurons,Neuron, Nociceptive,Neurons, Nociceptive,Nociceptive Neuron,Nociceptor,Pain Receptor
D010388	Pelvis	The space or compartment surrounded by the pelvic girdle (bony pelvis). It is subdivided into the greater pelvis and LESSER PELVIS. The pelvic girdle is formed by the PELVIC BONES and SACRUM.	Pelvic Region,Region, Pelvic
D010525	Peripheral Nerves	The nerves outside of the brain and spinal cord, including the autonomic, cranial, and spinal nerves. Peripheral nerves contain non-neuronal cells and connective tissue as well as axons. The connective tissue layers include, from the outside to the inside, the epineurium, the perineurium, and the endoneurium.	Endoneurium,Epineurium,Perineurium,Endoneuriums,Epineuriums,Nerve, Peripheral,Nerves, Peripheral,Perineuriums,Peripheral Nerve
D001743	Urinary Bladder	A musculomembranous sac along the URINARY TRACT. URINE flows from the KIDNEYS into the bladder via the ureters (URETER), and is held there until URINATION.	Bladder,Bladder Detrusor Muscle,Detrusor Urinae,Bladder Detrusor Muscles,Bladder, Urinary,Detrusor Muscle, Bladder,Detrusor Muscles, Bladder
D004558	Electric Stimulation	Use of electric potential or currents to elicit biological responses.	Stimulation, Electric,Electrical Stimulation,Electric Stimulations,Electrical Stimulations,Stimulation, Electrical,Stimulations, Electric,Stimulations, Electrical
D005073	Evoked Potentials, Somatosensory	The electric response evoked in the CEREBRAL CORTEX by stimulation along AFFERENT PATHWAYS from PERIPHERAL NERVES to CEREBRUM.	Somatosensory Evoked Potentials,Evoked Potential, Somatosensory,Somatosensory Evoked Potential