Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
BJU Int. 2012 Jan;109(1):132-40. doi: 10.1111/j.1464-410X.2011.10435.x. Epub 2011 Aug 29.
To study muscarinic/purinergic receptor activation and Rho-kinase/protein kinase C (PKC) signalling during smooth muscle contraction in normal and hypertrophic mouse urinary bladders.
Partial urinary outflow obstruction was induced in adult female (10-12 weeks) C57Bl/6 mice and comparisons were made with sham-operated controls. Bladder preparations were examined in vitro. Expression of signalling proteins was examined using Western blot analysis.
Obstructed bladders increased more than threefold in weight and were found to have enhanced muscarinic and attenuated purinergic components during nerve-induced contractions. The contractile response to carbachol was shifted towards lower concentrations of carbachol for the peak response and had a markedly enhanced sustained component. The amplitude of the α,β-methylene ATP-induced responses was lowered. Rho-kinase inhibitor Y27632 (10 µM) inhibited peak and sustained contractile responses to carbachol in control bladders (peak by 38%; plateau 57%) and obstructed bladders (peak 37% plateau 47%). PKC inhibitor GF109203X (1 µM) inhibited carbachol contractions in controls (peak by 29%; plateau 29%) and obstructed bladders (peak 17%; plateau 12%). Inhibition by a similar extent was observed after nerve stimulation. Sensitivity to Ca(2+) in high-K(+) depolarized intact tissues increased in obstructed bladders. This increased receptor-independent Ca(2+)-sensitivity was abolished by Y27632. Tissue contents of the myosin-binding phosphatase subunit MYPT-1 and catalytic phosphatase subunit PP1β, were decreased and the contents of RhoGDI, RhoA and CPI-17 increased. A decrease in the Rho-kinase isoform ROCK-1 was observed.
Based on these results, one can speculate that Rho-kinase inhibition would preferentially target the pathological phasic activity in the urinary bladder rather than inhibit the physiological receptor-mediated bladder emptying.
研究正常和肥厚的小鼠膀胱平滑肌收缩过程中毒蕈碱/嘌呤能受体激活和 Rho 激酶/蛋白激酶 C（PKC）信号转导。
在成年雌性（10-12 周龄）C57Bl/6 小鼠中诱导部分尿路流出梗阻，并与假手术对照进行比较。在体外检查膀胱标本。使用 Western blot 分析检查信号蛋白的表达。
梗阻的膀胱重量增加了三倍以上，并且在神经诱导收缩时发现具有增强的毒蕈碱和减弱的嘌呤能成分。乙酰胆碱引起的收缩反应的峰值反应向较低浓度的乙酰胆碱转移，并且具有明显增强的持续成分。α，β-亚甲基 ATP 诱导反应的幅度降低。Rho 激酶抑制剂 Y27632（10 µM）抑制了对照膀胱（峰值抑制 38%；平台期抑制 57%）和梗阻膀胱（峰值抑制 37%，平台期抑制 47%）中乙酰胆碱引起的峰值和持续收缩反应。PKC 抑制剂 GF109203X（1 µM）抑制了对照（峰值抑制 29%；平台期抑制 29%）和梗阻膀胱（峰值抑制 17%，平台期抑制 12%）中乙酰胆碱引起的收缩反应。神经刺激后观察到类似程度的抑制。在梗阻的膀胱中，高 K+去极化完整组织中对 Ca2+的敏感性增加。这种增加的受体非依赖性 Ca2+敏感性被 Y27632 消除。肌球蛋白结合磷酸酶亚基 MYPT-1 和催化磷酸酶亚基 PP1β 的组织含量减少，RhoGDI、RhoA 和 CPI-17 的含量增加。观察到 Rho 激酶同工型 ROCK-1 的减少。
基于这些结果，可以推测 Rho 激酶抑制将优先靶向膀胱的病理性相活性，而不是抑制生理性受体介导的膀胱排空。
