Expression Of Angiopoietin-Like Protein 2 Is Suppressed By Angiotensin Ⅱ Through Angiotensin Ⅱ Type 1 Receptor In Rat Cardiomyocytes

Objective:This study aimed to explore the inhibitory effect of angiotensin Ⅱ (AngⅡ) on angiopoietin-like protein 2 (Angptl2) in primary cardiomyocytes of rat and explain the potential identity of angiotensin Ⅱ type 1 receptor (ATIR) in this phenomenon.Methods:Cardiomyocytes were isolated from 3-day-old male Wistar rats. They were then cultured and identified. Subsequently, the expression level of Angptl2 was measured under different stimulus time and concentration using Western blot, reverse transcription-polymerase chain reaction, enzyme-linked immunosorbent assay, immunofluorescence, etc. Finally, under the most appropriate condition (stimulus of AngⅡ at 100 nmol/L for 24 h), cardiomyocytes were divided into six groups (normal, AngⅡ, Angll+losartan, normal+losartan, AngⅡ+PD123319, normal+PD123319) to investigate the possible function of ATIR in suppressing Angptl2. Losartan and PD123319 are agonists of ATIR and AT2R, respectively. Statistical analyses were performed using the Student’s t test or analysis of variance when necessary.Results:1. Identification of cardiomyocytes:The cellular morphology was observed under an optical microscope. The cardiomyocytes can be seen growing in a group, adhering to the bottom of the dish. The cardiomyocytes were detected to produce a certain beating rhythm under a microscope. Meanwhile, the identification of cardiomyocytes was also testified by detecting a-SMA under an inverted fluorescence microscope. The purity of cardiomyocytes in the isolated primary cells in this study was about 94%.2. Effect of various AngⅡ stimulus concentrations on cardiomyocytes:The data showed that under the stimulus condition 100 nmol/L Angll for 24 h, the protein expression of Angptl2 decreased more obviously than under other stimulus conditions compared with the normal (P< 0.05).3. Role of AT1R and AT2R antagonists:Under the stimulus condition 100 nmol/L Angll for 24 h, the AngⅡ+losartan group expressed more Angptl2 compared with the Angll group obviously (P< 0.05). The expression of Angptl2 in the normal+ losartan group and normal+PD123319 was approximately equal to that in the normal group (P>0.05), the expression level of Angptl2 in the AngⅡ+PD123319 group has no significant difference compared with the Angll group (P>0.05)Conclusion:1.AngⅡ can decrease Angptl2 expression level in cardiomyocytes.2.AngⅡ can regulate the expression of Angptl2 in cardiomyocytes by AT1R.3.Angptl2 may play a key role in the regulation of cardiac hypertrophy.