Malmqvist U, Arner A
Department of Physiology and Biophysics, University of Lund, Sweden.
Circ Res. 1990 Mar;66(3):832-45. doi: 10.1161/01.res.66.3.832.
Growth of the smooth muscle in the rat portal vein was initiated by an increased transmural pressure. After 7 days, the cross-sectional area of the vessel wall and the maximal active force of the longitudinal muscle layer had increased twofold. Electron microscopy showed that the cell cross-sectional area was increased, suggesting cellular hypertrophy. Increased amounts of intermediate (10 nm) filaments were observed in the hypertrophied cells. The hypertrophied vessels had decreased DNA content per unit wet weight compared with the control vessels (hypertrophied, 1.5 +/- 0.1; control, 1.9 +/- 0.1 micrograms/mg; p less than 0.01). Protein composition was studied with electrophoretic methods. Compared with control preparations the hypertrophied veins had similar myosin and actin contents per unit wet weight (myosin: hypertrophied, 4.4 +/- 0.8; control, 5.9 +/- 0.9; actin: hypertrophied 12.2 +/- 0.6; control, 11.8 +/- 1.0 mg/g). Two different forms of the myosin heavy chain were detected with 5% sodium dodecyl sulfate-polyacrylamide gels. The proportion of the lower molecular weight heavy chain relative to total heavy chain content was about 30% and similar in both preparations. The relation filamin/myosin was increased in the hypertrophied vessels. Pyrophosphate gel electrophoresis revealed two protein bands, with an increase in the slower migrating band in the hypertrophied vessels possibly reflecting an increase in filamin content in the extracts. In the control portal vein alpha-actin is the dominating isoform constituting about 55% of total actin. In hypertrophied vessels, alpha-actin decreased (by 15%) and gamma-actin increased (by 20%). The portal vein contained desmin and vimentin in a ratio of about 6:1. The hypertrophied vessels showed a marked increase in the amount of these proteins (desmin/actin: hypertrophied, 0.32; control, 0.14). In conclusion, during pressure-induced growth of the portal vein, contractile protein contents increase in proportion to the increase in weight. A change in isoforms of actin occurs but no evidence for a change in myosin isoforms was found. The structural proteins increase relative to tissue weight, possibly associated with the increased number of intermediate filaments demonstrated with electron microscopy.
大鼠门静脉平滑肌的生长是由跨壁压力增加引发的。7天后，血管壁的横截面积和纵肌层的最大主动力增加了两倍。电子显微镜显示细胞横截面积增加，提示细胞肥大。在肥大细胞中观察到中等（10纳米）丝的数量增加。与对照血管相比，肥大血管每单位湿重的DNA含量降低（肥大组，1.5±0.1；对照组，1.9±0.1微克/毫克；p<0.01）。采用电泳方法研究蛋白质组成。与对照制剂相比，肥大静脉每单位湿重的肌球蛋白和肌动蛋白含量相似（肌球蛋白：肥大组，4.4±0.8；对照组，5.9±0.9；肌动蛋白：肥大组12.2±0.6；对照组，11.8±1.0毫克/克）。用5%十二烷基硫酸钠-聚丙烯酰胺凝胶检测到两种不同形式的肌球蛋白重链。较低分子量重链相对于总重链含量的比例约为30%，且两种制剂中相似。肥大血管中细丝蛋白/肌球蛋白的关系增加。焦磷酸凝胶电泳显示两条蛋白带，肥大血管中迁移较慢的条带增加，可能反映提取物中细丝蛋白含量增加。在对照门静脉中，α-肌动蛋白是主要的异构体，约占总肌动蛋白的55%。在肥大血管中，α-肌动蛋白减少（15%），γ-肌动蛋白增加（20%）。门静脉中结蛋白和波形蛋白的比例约为6:1。肥大血管中这些蛋白质的含量显著增加（结蛋白/肌动蛋白：肥大组，0.32；对照组，0.14）。总之，在压力诱导门静脉生长过程中，收缩蛋白含量随重量增加而成比例增加。肌动蛋白异构体发生变化，但未发现肌球蛋白异构体变化的证据。结构蛋白相对于组织重量增加，可能与电子显微镜显示的中间丝数量增加有关。
