心肌細胞凋亡是心臟衰竭的重要原因之一，糖尿病和高血壓最終可能釀成心臟衰竭。我們想探討在糖尿病症與隨著年齡增長，在類胰島素生長因子-I接受體[insulin-like growth factor-I receptor (IGF-IR) ]產生阻抗和類胰島素生長因子-I [ insulin-like growth factor-I (IGF-I) ]減少的情況之下，血管昇壓素(Angiotensin II)存在的高血壓症是否可能引發加成性的心肌病變。本實驗同時採用成年大白鼠初代培養的心肌細胞和胚胎大白鼠心肌轉型細胞株，H9C2，將細胞培養於不含血清的培養液並使用血管昇壓素(Angiotensin II)、antisense IGF-I和IGF-I receptor antibody進行實驗。結果顯示血管昇壓素(Angiotensin II)、IGF-I減少和IGF-IR阻斷皆會引發心肌細胞肥大及心肌細胞凋亡的現象，其中包含心肌細胞表面積變大、DNA斷裂、細胞核濃染以及促細胞凋亡蛋白Bad的增加及粒腺體攜帶電子cytochrome c的漏失；更發現IGF-I減少及IGF-IR阻抗均可加乘促進血管昇壓素(Angiotensin II)的效果。但是加成性心肌細胞肥大、細胞凋亡和Bad蛋白產量增加與cytochrome c的漏失的現象均可在antisense IGF-II或IGF-II antibody的加入下而被抑制。同時發現在IGF-I減少及IGF-IR阻抗時均會誘發IGF-II和IGF-II receptor基因表現和蛋白量增加。綜合以上結果IGF-I減少及IGF-IR阻抗會加乘血管昇壓素(Angiotensin II)引發心肌細胞肥大和心肌細胞凋亡的作用，這可能與誘導IGF-II 及IGF-II receptor upregulation 有關。 Apoptosis of cardiac myocytes is one of the cause of heart failure. Hypertension and diabetes being able to lead to cardiomyocytes apoptosis, might eventually develop into heart failure. The main purpose of this study is to identify under the condition of hypertension induced by Angiotensin-II (Ang-II) whether the reduction of insulin-like growth factor-I (IGF-I) through aging and / or insulin-like growth factor-I receptor (IGF-IR) resistant of diabetic mellitus might further enhance heart failure.Applying primary cardiomyocytes from adult rat hearts and transforming embryonic heart cells of rat, H9C2 with serum-free medium, we added Ang-II with or without antisense IGF-I or IGF-IR antibodies to identify the heart failure-enhancing effects. Results show that with AngII treatment and IGF-I deficiencies induced both cardiomyocytes hypertrophy and apoptosis.An enlarged size、DNA fragmentation、nuclear condensation and elevating pro-apoptotic proteins, such as Bad and cytochrome c, appeared in both primary cardiomyocytes or H9C2. Particularly, the pro-apoptotic effects of Ang-II were augmented by IGF-I deficiency and anti-IGF-IR treatment. Insterestingly, the apoptosis and hypertrophy of cardiomyocytes, the increase of Bad protein and the release of cytochrome c were all reversed by antisense IGF-II or anti-IGF-II treatment. At the mean time, the upregulation of IGF-II and IGF-II receptor gene expression and protein production were both observed under IGF-I deficient and IGF-I receptor resistant. Taken together, our results suggested that cardiomyocyte hypertrophy and apoptosis caused by Ang-II were augmented by IGF-I deficiency and/or IGF-IR resistant, which might result comes from IGF-II gene up-regulation.
