目的：观察亚降压量氯沙坦和卡托普利对压力超荷大鼠心肌肌球蛋白重链（ＭＨＣ）基因表达的影响．方法：狭窄腹主动脉（ＡＡＣ）造成心脏压力超荷，以１８ＳｒＲＮＡ作内标，Ｎｏｒｔｈｅｒｎ杂交检测ＭＨＣｍＲＮＡ．结果：ＡＡＣ术后１２ｄ，左室心肌βＭＨＣ表达上调７０倍，αＭＨＣ表达降低仅２６％．术后ｄ２给予亚降压量氯沙坦（３ｍｇ·ｋｇ－１·ｄ－１，ｉｇ）和卡托普利（３０ｍｇ·ｋｇ－１·ｄ－１，ｉｇ）治疗１１天，能抑制ＣｏＡ心肌βＭＨＣ基因过量表达９６％，但不增强αＭＨＣ表达．结论：压力超荷导致βＭＨＣ表达上调．氯沙坦抑制βＭＨＣ表达与其直接阻滞心肌ＡＴ１受体有关，而不依赖血液动力学机制． AIM: To investigate the effects of losartan and captopril on the gene expression of myocardial myosin heavy chain (MHC) in pressure overload rats. Methods: Cardiac pressure overload was induced by stenosis of abdominal aorta (AAC). 18S rRNA was used as internal standard and Northern blot hybridization was used to detect MHC mRNA. Results: 12 h after AAC, the expression of βMHC in left ventricular myocardium was up to 70-fold and the expression of αMHC decreased by only 26%. Administration of losartan (3 mg · kg-1 · d-1, ig) and captopril (30 mg · kg-1 · d-1, ig) β  MHC gene over-expression 96%, but not enhance α  MHC expression. Conclusion: Pressure overload led to increased expression of βMHC. Losartan inhibition of β-MHC expression and its direct block myocardial AT1 receptor, and not dependent on hemodynamic mechanisms.