title: Botulinum toxin type A normalizes alterations in urothelial ATP and NO release induced by chronic spinal cord injury.
abstract: The purpose of this paper was to simultaneously examine changes in urothelial ATP and NO release in normal and spinal cord injured animals as well as in spinal cord injured animals treated with botulinum toxin type A (BoNT-A). Furthermore we correlated changes in transmitter release with functional changes in bladder contraction frequency, and determined the effects of BoNT-A on bladder efferent nerve function. Normal and spinal cord injured rat bladders were injected on day 0 with either vehicle (saline containing bovine serum albumin) or BoNT-A. On day 2, in vitro neurotransmitter release and bladder strip contractility studies as well as in vivo cystometrographic studies were conducted. Resting ATP release was significantly enhanced following spinal cord injury (i.e. 57% increase, p<0.05) and was unaffected by BoNT-A treatment. SCI increased hypoosmotic evoked urothelial ATP release by 377% (p<0.05). BoNT-A treatment reduced evoked ATP release in SCI bladders by 83% (p<0.05). In contrast, hypoosmotic stimulation induced NO release was significantly inhibited following SCI (i.e. 50%, p<0.05) but recovered in SCI rats treated with BoNT-A (i.e. 195% increase in NO release in SCI-BTX-treated rats compared to SCI controls, p<0.01). Changes in urothelial transmitter release coincided with a significant decrease in non-voiding bladder contraction frequency (i.e. 71%, p<0.05) in SCI-BTX rats compared to SCI rats. While no difference was measured between neurally evoked contractile amplitude between SCI and SCI-BTX animals, atropine (1 microM) inhibited contractile amplitude to a greater extent (i.e. 76%, p<0.05) in the SCI-BTX group compared to the SCI group. We hypothesize that alterations in the ratio of excitatory (i.e. ATP) and inhibitory (i.e. NO) urothelial transmitters promote bladder hyperactivity in rat bladders following SCI that can be reversed, to a large extent, by treatment with BoNT-A.
authors.affiliation: Scott Department of Urology, Baylor College of Medicine, One Baylor Plaza, Alkek N720, Houston, TX 77030, USA.
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Smith
authors.forename: David A
authors.initials: DA
authors.lastname: Gangitano
authors.forename: Alvaro
authors.initials: A
authors.lastname: Munoz
authors.forename: Nilson A
authors.initials: NA
authors.lastname: Salas
authors.forename: Timothy B
authors.initials: TB
authors.lastname: Boone
authors.forename: K Roger
authors.initials: KR
authors.lastname: Aoki
authors.forename: Joseph
authors.initials: J
authors.lastname: Francis
authors.forename: George T
authors.initials: GT
authors.lastname: Somogyi
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D019274:Botulinum Toxins, Type A / Q000494:pharmacology* / Q000627:therapeutic use; D002908:Chronic Disease; D004195:Disease Models, Animal; D005260:Female; D007001:Hypogastric Plexus / Q000187:drug effects / Q000503:physiopathology; D007038:Hypotonic Solutions / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D009130:Muscle, Smooth / Q000187:drug effects / Q000294:innervation / Q000503:physiopathology; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology; D009465:Neuromuscular Agents / Q000494:pharmacology; D018377:Neurotransmitter Agents / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D010275:Parasympathetic Nervous System / Q000187:drug effects / Q000503:physiopathology; D051381:Rats; D013119:Spinal Cord Injuries / Q000150:complications*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology; D001743:Urinary Bladder / Q000187:drug effects / Q000294:innervation / Q000503:physiopathology; D001750:Urinary Bladder, Neurogenic / Q000188:drug therapy* / Q000378:metabolism* / Q000503:physiopathology; D019459:Urothelium / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology
chemical_list: D007038:Hypotonic Solutions; D009465:Neuromuscular Agents; D018377:Neurotransmitter Agents; D009569:Nitric Oxide; D000255:Adenosine Triphosphate; D019274:Botulinum Toxins, Type A