[Effect of substance P on expression of beta1-adrenergic receptor in cultured rat cardiomyocytes].

OBJECTIVE: To investigate the effect of substance P (SP) on expression of beta1-adrenergic receptor (beta1-AR) in cultured neonatal rat cardiomyocytes. METHODS: Cardiomyocytes were obtained from 1-3 days old Sprague-Dawley (SD) rats and cultured for 72 hours. Six wells of the cultured cells were divided into two groups (n=3 in each group): control group and SP group (incubated with 10(-7) mol/L of SP). Immunocytochemistry was used to detect the expression of beta1-AR in cultured rat cardiomyocytes. Fifteen wells of the cultured cells were divided into five groups (n=3 in each group): control group and four SP groups (incubated with 10(-9), 10 (-8), 10(-7), 10(-6) mol/L of SP respectively). Quantitative analysis of the expression of beta1-AR in cultured neonatal rat cardiomyocytes of all the groups was performed using flow cytometry. RESULTS: The results of immunocytochemistry showed that the expression of beta1-AR in cardiomyocytes in SP group was lower than that in control group (positive unit: 179.16+/-48.18 vs. 205.79+/-117.42, average light density: 128.26+/-22.72 vs. 157.35+/-33.11, both P<0.05). The results of flow cytometry showed that significantly lower levels of expression of beta1-AR were observed in the groups treated with SP in the concentrations ranging from 10 (-8) mol/L to 10 (-6) mol/L (151.85+/-4.63,135.00+/-6.84,121.41+/-5.22 vs. 161.35+/-3.09,all P<0.05). CONCLUSION: SP could down-regulate the expression of beta1-AR in cultured rat cardiomyocytes in vitro.