To evaluate the effect of transfecting angiotensin Ⅱ receptor (AT1) anti-sense nucleotide (AT1A) on the expression of subtypes of Angiotensin Ⅱ (Ang Ⅱ ) receptor mRNA, and syntheses of protein and nucleic acid in cardiomyocytes. Methods: AT1 cDNA sequence (476 bp) was cloned with RT-PCR and inserted into PcDNA3.1 (5.4 kb) anti-sensely to construct an intact plasmid containing AT1A(PAT1A). It was transfected into the cultured cardiomyocytes, which was identified with RT-PCR and West blot. Syntheses of protein and nucleic acid were determined with 3H-Leu and 3H-TdR incorporation, mRNA expressions of AT1 and AT2 were observed with RT-PCR. Transfected and nontransfected cardiomyocytes were compared after stimulated for 24 h by AngⅡ 1 × 10-7mol/L. Results: We constructed PAT1A successfully. AT1 mRNA and protein were expressed significantly less in transfected cardiomyocytes than that in the control (P＜0.01). AT1 mRNA expression was markedly decreased, and AT2 mRNA obviously increased (P＜0.01); but no apparent difference was found in 3H-Leucine (3H-Leu) and 3H-Thymidine (3H-TdR) incorporation between the transfected and nontransfected cardiomyocytes after stimulated for 24 h of Ang Ⅱ 10-7 mol/L (P＞0.05). Conclusion: After blocked with AT1A, expression of AT1mRNA in cultured cardiomyocytes was markedly suppressed,while AT2 mRNA was up-regulated at the same time. This fact suggests that syntheses of both protein and nucleic acid in cardiomycytes mediated with Ang Ⅱ could not be effectively interrupted simply with AT1A blocking.