Changes of bladder activity and connexin 43-derived gap junctions after partial bladder-outlet obstruction in rats.
BACKGROUND
We investigated changes of vesical gap junctions in relation to changes of the micturition reflex in rats with partial bladder-outlet obstruction (BOO).


METHODS
A total of 66 female Sprague-Dawley rats were divided into six groups: sham operation (control); 3, 14, and 28 days after BOO; and 3 and 28 days after relief of BOO lasting for a three-day period. Under urethane anesthesia, isovolumetric cystometry was performed on each group. Expression of mRNA for the gap-junction protein connexin 43 (Cx43) in the bladder was measured in each group. Immunohistochemistry using Cx43 antibody was also performed on the bladder after BOO.


RESULTS
The interval between bladder contractions was shorter in all of the other groups than in the control group. Expression of Cx43 mRNA was increased 3, 14, and 28 days after BOO (the peak increase was twofold), and three days after the relief of BOO, but it returned to the control level by 28 days after relief of BOO. Histologically, smooth muscle hypertrophy was detected in the bladder after BOO and punctate staining of the smooth muscle by Cx43 antibody increased after BOO.


CONCLUSIONS
These results suggest that partial BOO produces detrusor overactivity that may depend on increased intercellular communication via gap junctions in the bladder. Relief of BOO led to a decrease of Cx43 mRNA, but detrusor overactivity persisted in the chronic phase, suggesting a reversible change of vesical gap junctions and an irreversible change of bladder activity after BOO.
Miyazato
Minoru
M
Division of Urology, Department of Organ-Oriented Medicine, Faculty of Medicine, University of the Ryukyus, 207 Uehara, Nishihara, Okinawa, 903-0215, Japan. Mmiya929@med.u-ryukyu.ac.jp
Sugaya
Kimio
K
Nishijima
Saori
S
Kadekawa
Katsumi
K
Machida
Noriko
N
Oshiro
Yoshinori
Y
Saito
Seiichi
S
D000818:Animals; D018031:Connexin 43 / Q000235:genetics / Q000378:metabolism*; D004195:Disease Models, Animal; D005260:Female; D017629:Gap Junctions / Q000378:metabolism* / Q000473:pathology; D007150:Immunohistochemistry; D009119:Muscle Contraction / Q000502:physiology; D009130:Muscle, Smooth / Q000503:physiopathology; D012333:RNA, Messenger / Q000378:metabolism; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012016:Reference Values; D001748:Urinary Bladder Neck Obstruction / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D016055:Urinary Retention / Q000503:physiopathology; D014554:Urination
D018031:Connexin 43; D012333:RNA, Messenger