방광내 아데노신 트리포스페이트 주입으로 유발된 백서방광의 배뇨근과활동성의 특징

Abstract

방광의 배뇨근, 점막, 점막하 신경에는 퓨린성 수용체가 분포하며 배뇨반사에 관여한다. 방광점막은 아데노신 트리포스페이트 (adenosine 5'-triphosphate; ATP)를 분비하며 방광충만시 점차 분비량이 증가하여 퓨린성 수용체 자극을 통한 방광의 감각 기전에 작용한다. 병적인 상태에서는 방광점막의 ATP분비가 증가하여 빈뇨 등의 하부요로증상을 유발한다. 본 연구는 ATP의 방광내 주입으로 유도된 배뇨근과활동성 동물모델의 특성을 알아 보고자 시행되었다. 생후 8주의 암컷 Sprague-Dawley 백서에 방광루를 설치하여 urethane (1.2g/kg) 마취하에 방광내압측정술을 시행하였다. 방광루를 통해 프로타민 설페이트 (protamine sulfate; PS, 10mg/ml)를 60분간 주입 (0.04ml/min)하여 방광의 기능적 장벽을 제거한 후 ATP (60mM, pH 6.0)를 주입 (0.04ml/min)하면서 요역동학검사를 시행하여 수축간간격, 최대배뇨압, 배뇨역치압 및 초기방광압을 비교하였으며, 각 배뇨기간의 방광내압 증가속도 (Ph1slope), 최대방광압 (Ph1MBP, Ph2MBP, Ph3MBP), 평균방광압 (Ph2meanBP) 및 방광내압의 빠른 진동 (intraluminal pressure high-frequency oscillations; IPHFOs)의 변화를 측정하였다. 대퇴정맥의 정맥도관을 통하여 P2X 수용체의 길항체인 피리독살 포스페이트 아조페닐 디설포닉 산 (pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid; PPADS)을 정맥주사하여 ATP에 의해 유도된 배뇨근과활동성의 요역동학지표 변화를 관찰하였다. 수축간간격은 PS 주입시에는 별다른 차이가 없었으나 (544.2±67.2s vs 462.9±40.9s, p=0.074), ATP 주입 후 유의하게 짧아졌다 (222.3± 170.8s, p=0.001). 최대배뇨압은 PS 주입시 유의하게 감소하였고 (31.3±4.7cmH2O vs 26.4±3.8cmH2O, p=0.001), ATP주입시 감소폭이 더욱 커졌다 (25±2.9cmH2O, p=0.001). 배뇨역치압과 초기방광압은 PS 주입으로 별다른 영향이 없었으나 (4.0±1.3cmH2O vs 3.4±1.6cmH2O, p=0.113/8.8±2.6cmH2O vs 8.0±1.6cmH2O, p=0.140), ATP의 주입으로 대조군에 비하여 현저히 감소하였다 (1.4±0.8cmH2O, p=0.001/6.6±1.3cmH2O, p=0.01). 방광내 ATP 주입에 의한 수축간간격, 최대배뇨압, 배뇨역치압 및 초기방광압의 변화는 PPADS 정맥주사로 반전되어 대조군 값으로 회복되었다. 배뇨주기 별로 Ph1slope은 PS 주입으로 대조군에 비하여 유의하게 감소하였으며 (4.5±1.0cmH2O/s vs 3.8±0.8cmH2O/s, p=0.029), ATP 주입시에는 그 차이가 더욱 현저해 졌다 (2.3±0.9cmH2O/s, p=0.001). Ph1MBP, Ph2MBP, Ph2meanBP는 PS주입시부터 유의하게 감소하기 시작하여 ATP주입으로 더욱 감소하였다. Ph3MBP에서 PS 주입으로 유의하게 감소하여 (27.5±3.7cmH2O vs 21.6±3.8cmH2O, p=0.001), ATP 주입 후에도 유의하게 감소되어 있었다 (23.6±3.5cmH2O, p=0.001). PS와 ATP의 방광내 주입에 따른 IPHFOs의 변화는 보이지 않았다. 백서에서 방광내 ATP의 주입은 배뇨근과활동성을 유발하였으며, 방광내 ATP는 배뇨기에 작용하지 않고 요저장기에 작용하여 배뇨근과활동성을 유발하였다.; Purinergic receptors are distributed through bladder detrusor muscle, epithelium & subepithelial nerves, and control voiding reflex. With mechanical stretch, adenosine 5'-triphosphate (ATP) release was increased in bladder. So bladder epithelium, which release ATP, can act on bladder sensory mechanism mediated by activating purinergic receptors. In a state of pathology, ATP release from bladder epithelium increase and secondly induce lower urinary tract symptom. This study investigated characteristics of detrusor overactivity induced by the intravesical application of ATP. Under urethane anesthesia continuous cystometrogram was performed cystostomy in 8 weeks olds Sprague-Dawley female rats at infusion rate of 0.04ml/min. After infusion of protamine sulfate (PS, 10mg/mL) for 60 min., ATP (60mM, pH 6.0) was continuously infused intravesically. The effects of intravenous injection of pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS) was studied during intravesical application of ATP. Cystometric parameters, consist of intercontraction interval (ICI), maximal voiding pressure (MVP), pressure threshold (PT), baseline bladder pressure (BBP) were compared respectively. Micturition cycle was divided into four phases. On the first voiding phase, bladder pressure increase rate (slope; Ph1slope) was measured. On the each voiding phases, maximal bladder pressure (Ph1MBP, Ph2MBP, Ph3MBP), mean bladder pressure (Ph2meanBP) and variation of intraluminal pressure high-frequency oscillations (IPHFOs) were measured, respectively. In the intravesical application of PS, ICI had no difference between control and PS (544.2±167.2s vs 462.9±140.9s, p=0.074), but were decreased significantly by intravesical application of ATP (222.3±170.8s, p=0.001). MVP was decreased significantly after intravesical application of PS (31.3±4.7cmH2O vs 26.4±3.8cmH2O, p=0.001), further decreased after intravesical application of ATP (25±2.9cmH2O, p=0.001). The intravesical application of PS did not have particular effect on PT & BBP (4.0±1.3cmH2O vs 3.4±1.6cmH2O, p=0.113/8.8±2.6cmH2O vs 8.0±1.6cmH2O, p=0.140), but intravesical application of ATP were decreased PT & BBP significantly compared with control, respectively (1.4±0.8cmH2O, p=0.001/6.6±1.3cmH2O, p=0.001). Variation of ICI, PT & BBP induced by intravesical application of ATP were reversed by intravenous injection of PPADS. Ph1slope was decreased after intravesical application of PS (4.5±1.0cmH2O/s vs 3.8±0.8cmH2O/s, p=0.029), and further decreased after intravesical application of ATP (2.3±0.9cmH2O/s, p=0.001). Also Ph1MBP, Ph2MBP & Ph2meanBP were decreased after intravesical application of PS, and further decreased after intravesical application of ATP, respectively. Ph3MBP was decreased significantly intravesical application of PS (27.5±3.7cmH2O vs 21.6±3.8cmH2O, p=0.001), and further decreased after intravesical application of ATP (23.6±3.5cmH2O, p=0.001). IPHFOs was not shown any difference between intravesical application of PS and ATP. Intravesical application of ATP into female rats induce detrusor overactivity, and ATP induce detrusor overactivity by acting on urine storage phase, not micturition phase.