title: Carbachol-induced volume adaptation in mouse bladder and length adaptation via rhythmic contraction in rabbit detrusor.
abstract: The length-tension (L-T) relationships in rabbit detrusor smooth muscle (DSM) are similar to those in vascular and airway smooth muscles and exhibit short-term length adaptation characterized by L-T curves that shift along the length axis as a function of activation and strain history. In contrast to skeletal muscle, the length-active tension (L-T(a)) curve for rabbit DSM strips does not have a unique peak tension value with a single ascending and descending limb. Instead, DSM can exhibit multiple ascending and descending limbs, and repeated KCl-induced contractions at a particular muscle length on an ascending or descending limb display increasingly greater tension. In the present study, mouse bladder strips with and without urothelium exhibited KCl-induced and carbachol-induced length adaptation, and the pressure-volume relationship in mouse whole bladder displayed short-term volume adaptation. Finally, prostaglandin-E(2)-induced low-level rhythmic contraction produced length adaptation in rabbit DSM strips. A likely role of length adaptation during bladder filling is to prepare DSM cells to contract efficiently over a broad range of volumes. Mammalian bladders exhibit spontaneous rhythmic contraction (SRC) during the filling phase and SRC is elevated in humans with overactive bladder (OAB). The present data identify a potential physiological role for SRC in bladder adaptation and motivate the investigation of a potential link between short-term volume adaptation and OAB with impaired contractility.
authors.affiliation: Department of Mechanical & Nuclear Engineering, Virginia Commonwealth University, Richmond, 23284-3015, USA. jespeich@vcu.edu
authors.forename: John E
authors.initials: JE
authors.lastname: Speich
authors.forename: Cameron W
authors.initials: CW
authors.lastname: Wilson
authors.forename: Atheer M
authors.initials: AM
authors.lastname: Almasri
authors.forename: Jordan B
authors.initials: JB
authors.lastname: Southern
authors.forename: Adam P
authors.initials: AP
authors.lastname: Klausner
authors.forename: Paul H
authors.initials: PH
authors.lastname: Ratz
mesh_terms: D018712:Analgesics, Non-Narcotic / Q000494:pharmacology*; D000818:Animals; D001683:Biological Clocks / Q000187:drug effects*; D002217:Carbachol / Q000494:pharmacology*; D015232:Dinoprostone / Q000494:pharmacology; D005260:Female; D051379:Mice; D009119:Muscle Contraction / Q000187:drug effects*; D009929:Organ Size / Q000187:drug effects; D010120:Oxytocics / Q000494:pharmacology; D011817:Rabbits; D001743:Urinary Bladder / Q000033:anatomy & histology / Q000502:physiology*
chemical_list: D018712:Analgesics, Non-Narcotic; D010120:Oxytocics; D002217:Carbachol; D015232:Dinoprostone