Contractile properties of the developing fetal sheep bladder.
OBJECTIVE
To characterise the developmental changes to the normal bladder by examining the in vitro contractile properties of the fetal sheep detrusor smooth muscle bladder at different gestational ages.


METHODS
Three groups of normally developing fetal sheep bladders were investigated: (1) 65-70 days gestation (2nd trimester); (2) 105-110 days (3rd trimester); (3) 135-140 days (term). Isometric contractions in isolated detrusor strips were measured during either electrical field stimulation (EFS) or exposure to agonists: carbachol, alpha-beta methylene-ATP (ABMA) and KCl.


RESULTS
There was a significant increase of absolute force elicited by EFS with fetal age. Contractures elicited by carbachol, ABMA and KCl increased between Groups 1 and 2, but not thereafter. The proportional increase of contractions elicited by carbachol and ABMA was also greater between Groups 1 and 2, than for EFS and KCl.


CONCLUSIONS
Fetal development between 65 and 140 days in the sheep is associated with increased contractile activation. The data are consistent with an increase of muscle development in the earlier stages (65-110 days). In the later stage (110-140 days) muscle development is complete but functional innervation of the tissue continues.
Nyirády
Peter
P
Semmelweis University Department of Urology, Budapest, Hungary. nyiradyp@hotmail.com
Thiruchelvam
Nikesh
N
Godley
Margaret L
ML
David
Anna
A
Cuckow
Peter M
PM
Fry
Christopher H
CH
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology; D018679:Cholinergic Agonists / Q000494:pharmacology; D004558:Electric Stimulation; D005260:Female; D005865:Gestational Age; D066298:In Vitro Techniques; D007537:Isometric Contraction / Q000187:drug effects / Q000502:physiology*; D009130:Muscle, Smooth / Q000196:embryology / Q000294:innervation / Q000502:physiology; D011189:Potassium Chloride / Q000494:pharmacology; D011247:Pregnancy; D012756:Sheep; D001743:Urinary Bladder / Q000196:embryology* / Q000294:innervation / Q000502:physiology*
D000970:Antineoplastic Agents; D018679:Cholinergic Agonists; D011189:Potassium Chloride; D000255:Adenosine Triphosphate; D002217:Carbachol; C002630:alpha,beta-methyleneadenosine 5'-triphosphate