[Role of Na(+)-K(+)-ATPase in lipopolysaccharide-induced cardiomyocyte hypertrophy in rats].

Objective To explore the possible mechanism of lipopolysaccharide(LPS)-induced cardiomyocyte hypertrophy in rats.Methods Neonatal rat cardiomyocytes cultured in vitro were stimulated with 100 μg/L LPS for1,4 or8 h and scanned by atomic force microscopy(AFM) for measurement of the two-dimensional area,three-dimensional surface area and volume of each cell.The total proteins and Na+-K+-ATPase activity in the cardiomyocytes were determined.The same measurements were also carried out in neonatal rat cardiomyocyte cultures stimulated by 0.5 μmol/L ouabain for 8 h and the total protein levels were measured.Results Following a 8-hour stimulation with LPS,the two-dimensional area,three-dimensional surface area and volume of the single cardiomyocyte became enlarged and the total cellular proteins increased significantly as compared with those in the normal control cells(P0.05).LPS treatment for 4 and 8 h resulted in significantly decreased activity of Na+-K+-ATPase in the cardiomyocytes(P0.05).In the cells treated with ouabain for8 h,the two-dimensional area,three-dimensional surface area,volume of the single cardiomyocyte and the total cellular proteins increased significantly in comparison with the normal control group(P0.05).Conclusion LPS can result in cardiomyocyte hypertrophy in rats possibly in relation to lowered Na+-K+-ATPase activity in the cardiomyocytes afterLPS exposure.