Muscarinic stimulation of the mouse isolated whole bladder: physiological responses in young and ageing mice.
1 Peripheral autonomous bladder activity is an incompletely understood property that may be important both in normal bladder function and in functional problems of the lower urinary tract. We describe how a muscarinic agonist, arecaidine, influences intravesical pressure and intramural bladder contractions in the isolated mouse and how response varies in ageing mice. 2 A group of 12 mice aged 3-4 months was compared with an 'ageing' group of 12 mice age 28-34 months. Bladders were microsurgically removed and mounted in whole organ tissue baths. The effects of the muscarinic agonist arecaidine on intravesical pressure and intramural contractions were performed at different bladder volumes. 3 In normal mice, arecaidine elicited tonic and phasic contractions, the latter showing a more substantial increase in amplitude with bladder distension. Localized 'micromotion' contractions were seen in the bladder wall, with regional differences arising after exposure to arecaidine. A background release of acetylcholine was inferred from the pressure increase induced by the cholinesterase inhibitor physostigmine. 4 Both micromotion activity and the phasic component of the arecaidine response were substantially reduced in ageing mice; the tonic component was preserved in the same specimens. 5 We conclude that the enhanced pressure fluctuations seen at high bladder volumes may act as a peripheral determinant of bladder capacity, and that changes in such activity may contribute to altered functional capacity and lower urinary tract symptoms in ageing individuals.
Lagou
M
M
Urophysiology Research Group, School of Surgical Sciences, University of Newcastle, Newcastle-upon-Tyne, UK.
Gillespie
J
J
Kirkwood
T
T
Harvey
I
I
Drake
M J
MJ
D000367:Age Factors; D000375:Aging / Q000502:physiology*; D000818:Animals; D001115:Arecoline / Q000031:analogs & derivatives / Q000494:pharmacology; D002800:Cholinesterase Inhibitors / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D066298:In Vitro Techniques; D051379:Mice; D008810:Mice, Inbred C57BL; D018721:Muscarinic Agonists / Q000494:pharmacology*; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000378:metabolism; D010830:Physostigmine / Q000494:pharmacology; D011976:Receptors, Muscarinic / Q000187:drug effects* / Q000378:metabolism; D001743:Urinary Bladder / Q000187:drug effects* / Q000378:metabolism; D014555:Urination Disorders / Q000378:metabolism
D002800:Cholinesterase Inhibitors; D018721:Muscarinic Agonists; D011976:Receptors, Muscarinic; C015688:arecaidine; D001115:Arecoline; D010830:Physostigmine