Protection of astragalus polysaccharide on lipopolysaccharide-induced cardiac myocytes hypertrophy of rats Preparation condition optimization of astragalus polysaccharide liposome by orthogonal test Preparation condition optimization of astragalus polysaccharide liposome by orthogonal test Protection of astragalus polysaccharide on lipopolysaccharide-induced cardiac myocytes hypertrophy of rats