Paulis L, Vazan R, Simko F, Pechánová O, Styk J, Babál P, Janega P
Institute of Pathophysiology, School of Medicine, Comenius University, Bratislava, Slovak Republic.
Physiol Res. 2007;56 Suppl 2:S71-S76. doi: 10.33549/physiolres.931400. Epub 2007 Sep 5.
Although exposure to continuous light is associated with hypertension and modulates the outcome of ischemia-reperfusion injury, less attention has been paid to its effects on cardiac morphology. We investigated whether 4-week exposure of experimental rats to continuous 24 h/day light can modify cardiac morphology, with focus on heart weight, fibrosis and collagen I/III ratio in correlation with NO-synthase expression. Two groups of male adult Wistar rats were studied: controls exposed to normal light/dark cycle (12 h/day light, 12 h/day dark) and rats exposed to continuous light. After 4 weeks of treatment the absolute and the relative heart weights were determined and myocardial fibrosis and collagen type I/III ratio were evaluated using picrosirius red staining. Endothelial and inducible NO-synthase expression was detected immunohistochemically. The exposure of rats to continuous light resulted in an increase of body weight with proportionally increased heart weight. Myocardial fibrosis remained unaffected but collagen I/III ratio increased. Neither endothelial nor inducible NO-synthase expression was altered in light-exposed rats. We conclude that the loss of structural homogeneity of the myocardium in favor of collagen type I might increase myocardial stiffness and contribute to functional alterations after continuous light exposure.
尽管持续光照与高血压有关，并能调节缺血再灌注损伤的结果，但人们对其对心脏形态的影响关注较少。我们研究了实验大鼠每天持续24小时光照4周是否会改变心脏形态，重点关注心脏重量、纤维化以及与一氧化氮合酶表达相关的I/III型胶原蛋白比例。研究了两组成年雄性Wistar大鼠：一组为暴露于正常光暗循环（每天12小时光照，12小时黑暗）的对照组，另一组为暴露于持续光照的大鼠。治疗4周后，测定绝对和相对心脏重量，并使用天狼星红染色评估心肌纤维化和I/III型胶原蛋白比例。通过免疫组织化学检测内皮型和诱导型一氧化氮合酶的表达。大鼠暴露于持续光照导致体重增加，心脏重量也相应增加。心肌纤维化未受影响，但I/III型胶原蛋白比例增加。光照大鼠的内皮型和诱导型一氧化氮合酶表达均未改变。我们得出结论，心肌结构同质性丧失，有利于I型胶原蛋白，可能会增加心肌僵硬度，并导致持续光照后功能改变。
