過伸展膀胱のdenervation supersensitivityに関する実験的研究

Abstract

雌性雑種成犬の膀胱に, 短時間(1時間), 長時間(48時間)の過伸展状態を作成し, 解除2週間後膀胱容量, 膀胱内圧の変化と利尿筋切片のAchに対する収縮反応の変化を調べた.膀胱容量, 膀胱内圧は感染の影響もあり一定の傾向は見出しえなかったが, 非感染群は7頭中6頭に膀胱容量の増加を, 感染群は5頭中4頭に膀胱容量の減少を認めた.感染は膀胱過伸展の両群で42%に認めた.Achに対する収縮反応は, 短時間群, 長時間群とも無処置群に比しあきらかに大きな収縮反応を示し, さらに長時間群では, Ach 10-8 g/ml以下の低濃度域でも収縮反応をみた

The influence of prolonged bladder overdistension on the detrusor muscle was studied in female mongrel dogs. Two overdistending methods were employed, namely, constantly elevated hydrostatic pressure for one hour and bladder neck ligation for 48 hours. The cystometrogram and urinalysis at 2 weeks after release of overdistension were compared with the preoperative estimations. Using the in vitro isometric technique, the contractility of the detrusor muscle strip to acetylcholine was evaluated in the untreated control group and the two overdistended groups. Prolonged bladder overdistension for one hour as well as 48 hours resulted in a high incidence of urinary tract infection. There was no correlation between the cystometric findings before and after overdistension . An increase in contraction response to acetylcholine was observed in both overdistended groups. Besides, a small contraction response to acetylcholine at a lower concentration was observed in the group overdistended for 48 hours. It is suggested that the observed contraction response increase was probably due to axonal degeneration caused by a decrease in the blood supply to the overdistended bladder wall.