Angiopoietin-like protein 2 expression is suppressed by angiotensin II via the angiotensin II type 1 receptor in rat cardiomyocytes

The present study aimed to determine the inhibitory effects of angiotensin II (AngII) on angiopoietin-like protein 2 (Angptl2) in rat primary cardiomyocytes, and to investigate the potential association between angiotensin II type 1 receptor (AT1R) and these effects. Cardiomyocytes were isolated from 3-day-old Wistar rats, and were cultured and identified. Subsequently, the expression levels of Angptl2 were detected following incubation with various concentrations of AngII for various durations using western blotting, reverse transcription-quantitative polymerase chain reaction, enzyme-linked immunosorbent assay and immunofluorescence. Finally, under the most appropriate conditions (100 nmol/l AngII, 24 h), the cardiomyocytes were divided into six groups: Normal, AngII, AngII + losartan, normal + losartan, AngII + PD123319 and normal + PD123319 groups, in order to investigate the possible function of AT1R in Angptl2 suppression. Losartan and PD123319 are antagonists of AT1R and angiotensin II type 2 receptor, respectively. The statistical significance of the results was analyzed using Student's t-test or one-way analysis of variance. The results demonstrated that Angptl2 expression was evidently suppressed (P<0.05) following incubation with 100 nmol/l AngII for 24 h. Conversely, the expression levels of Angptl2 were significantly increased in the AngII + losartan group compared with the AngII group (P<0.01). However, no significant difference was detected between the AngII + PD123319, normal + losartan or normal + PD123319 groups and the normal group. The present in vitro study indicated that AngII was able to suppress Angptl2 expression, whereas losartan was able to significantly reverse this decrease by inhibiting AT1R.