一氧化氮合成酵素及過氧化氫酵素基因經由腺病毒媒介傳送入心臟細胞對內皮素所誘發細胞肥大的抑制作用

Abstract

大多數心血管方面的疾病，都會造成 心臟的肥大，初期的心臟肥大可以代償心 臟功能，然而持續性的心臟肥大，便會導 致心臟的衰竭。在心臟細胞，由於機械應 力或內生性生長因子的刺激作用下，會造 成心臟細胞的肥大，心臟細胞的過度肥大 有可能導致心臟機能受損，進一步引起心臟衰竭。內皮素(endothelin-1; ET-1)有 造成細胞肥大的作用，但對於此作用其細 胞內的機轉目前還不是很清楚，已知內皮 素可增加許多迅即基因如c-fos 、c-jun 及 egr-1 等的基因表現；另外，對一些與心 臟細胞的增大有關的基因如心房利鈉 (atrial natriuretic peptide)、肌凝蛋 白重鏈(myosin heavy chain)、骨骼肌肉 肌動蛋白(actin)等，也有增加它們基因表 現的作用。近來有許多研究報告指出活性 氧族群(r eactive oxygen species ;ROS )及一氧化氮(nitric oxide; NO)可於細胞內 扮演一訊號傳遞者的角色，所以在本研究 中，我們進一步觀察一氧化氮合成酵素及 過氧化氫酵素基因經由腺病毒媒介傳送入 心臟細胞是否對內皮素所誘發細胞肥大產 生抑制的作用，並進而闡釋其可能的細胞 內機轉。由本報告一氧化氮合成酵素基因 經由腺病毒媒介傳送入心臟細胞可抑制內 皮素所誘發心臟細胞肥大，可推測一氧化 氮合成酵素基因經由腺病毒媒介傳送入心 臟細胞，在臨床上相關心臟肥大或心臟衰竭疾病的預防治療上具有運用潛力。

Cardiomyocyte hypertrophy play a transition step in the pathogenesis of heart failure. The objectives of this study were to determine whether transfer of recombinant endothelial nitric oxide synthase (eNOS) gene to neonatal rat cardiomyocytes would result in expression of a functional enzyme and to assess the effect of expression of eNOS on cardiomyocyte hypertrophy. Cardiomyocytes were transduced in vitro with adenoviral vectors encoding cDNA for eNOS (AdeNOS) and PGK empty vector. In contrast to AdPGK-transduced cells, cardiomyocytes transduced with AdeNOS increased calcium-dependent NOS activity (measured by the conversion of [ 3 H]L-arginine to [ 3 H]L-citrulline) and produced increased amounts of nitrite. Cardiomyocytes transduced with AdeNOS showed diminished endothelin-1 (ET-1)-stimulated protein synthesis as measured by [ 3 H]-leucine uptake. The present study demonstrates that adenovirus-mediated gene transfer of eNOS to cardiomyocytes results in the expression of a functional enzyme. Expression of recombinant eNOS in cardiomyocytes results in inhibition of ET-1-stimulated protein synthesis. These findings imply that eNOS gene transfer to cardiomyocytes may be a unique mode of increasing local NO production in the heart.