Developmental changes in Ca2+ homeostasis and contractility in gallbladder smooth muscle
Developmental changes in Ca2+ homeostasis and contractility in gallbladder smooth muscle
复制标题
DOI：
10.1152/ajpcell.00452.2008
复制
发表时间：
2009-04-01
影响因子：
5.5
通讯作者：
Pozo, Maria J.
中科院分区：
文献类型：
--
作者：
Camello-Almaraz, Cristina;Macias, Beatriz;Pozo, Maria J.
Camello-Almaraz C，Macias B，Gomez-Pinilla PJ，Alcon S，Martin-Cano FE，Baba A，Matsuda T，Camello PJ，Pozo MJ.胆囊平滑肌Ca 2+稳态和收缩力的发育变化。美国生理学杂志细胞生理学296：C783-C791，2009年。首次发表于2009年2月11日; doi：10.1152/ajpcell.00452.2008。相对知之甚少的贡献钙依赖性和非依赖性机制的新生儿胃肠平滑肌的收缩。因此，我们研究了10日龄和成年豚鼠胆囊平滑肌中的钙稳态和钙敏化机制，以阐明这些过程中的发育变化。胆囊收缩力进行了评估，等距张力记录从条，细胞内Ca 2+浓度进行了估计，通过荧光显微镜的Fura-2负载的分离的细胞，蛋白质表达和磷酸化进行了评估，通过Western印迹分析。新生儿胆囊收缩CCK显着低于成人组织，但这与增加Ca 2+动员，表明不成熟的Ca 2+敏化机制。新生儿胆囊中Ca 2+释放的增强是可释放Ca 2+池大小增加的结果。此外，在新生平滑肌细胞中，质膜Ca 2+泵和Na+/Ca 2+交换器都不参与Ca 2+的排出。相反，在这些细胞中，受磷蛋白磷酸化增加，这可能导致肌浆网（内）Ca 2 +-ATP酶泵过度活性。新生儿组织中Ca 2+敏感性的降低通过对Rho激酶（ROCK）抑制剂Y-27362和PKC抑制剂GF-109203 X对激动剂诱导的收缩缺乏作用来证明。此外，新生儿胆囊显示RhoA、ROCK、PKC和两种效应物[17 kDa的C激酶依赖性抑制剂（CPI-17）和靶向肌球蛋白磷酸酶1（MYPT 1）]水平较低，以及缺乏CPI-17和MYPT 1磷酸化对激动剂的反应。总之，我们的研究结果表明，平滑肌收缩的主要机制是在发育调节。
Camello-Almaraz C, Macias B, Gomez-Pinilla PJ, Alcon S, Martin-Cano FE, Baba A, Matsuda T, Camello PJ, Pozo MJ. Developmental changes in Ca2+ homeostasis and contractility in gallbladder smooth muscle. Am J Physiol Cell Physiol 296: C783-C791, 2009. First published February 11, 2009; doi:10.1152/ajpcell.00452.2008.-Relatively little is known about the contribution of Ca2+-dependent and -independent mechanisms in the contractility of neonatal gastrointestinal smooth muscle. We therefore studied Ca2+ homeostasis and Ca2+ sensitization mechanisms in 10-day-old and adult guinea pig gallbladder smooth muscle to elucidate developmental changes in these processes. Gallbladder contractility was evaluated by isometrical tension recordings from strips, intracellular Ca2+ concentration was estimated by epifluorescence microscopy of fura-2-loaded isolated cells, and protein expression and phosphorylation were assessed by Western blot analysis. The neonatal gallbladder contracted significantly less to CCK than adult tissue, but this correlated with an increased Ca2+ mobilization, suggesting immaturity of Ca2+ sensitization mechanisms. The enhanced Ca2+ release in the newborn gallbladder was the result of the increase in the size of the releasable Ca2+ pool. Moreover, in neonatal smooth muscle cells, neither the plasma membrane Ca2+ pump nor the Na+/Ca2+ exchanger collaborate in the extrusion of Ca2+. In contrast, in these cells, there is an increase in phospholamban phosphorylation, which could drive to an overactivity of the sarco(endo) plasmic reticulum Ca2+-ATPase pump. The reduced Ca2+ sensitivity in neonatal tissues was demonstrated by the lack of effect to Y-27362, an inhibitor of Rho kinase (ROCK), and GF-109203X, an inhibitor of PKC, on agonist-induced contraction. In addition, the neonatal gallbladder showed lower levels of RhoA, ROCK, PKC, and two effectors [C-kinase-dependent inhibitor of 17 kDa (CPI-17) and myosin phosphatase targetting 1 (MYPT1)] as well as an absence of CPI-17 and MYPT1 phosphorylation in response to agonists. In conclusion, our results indicate that the main mechanisms involved in smooth muscle contractility are under developmental regulation.