Study on morphology and surface antigen of primary cultured neonatal rats' sinoatrial node cells

Objective: To understand morphological characteristics of sinoatrial node cells (SNCs) by taking purified isolation and culture of neonatal rat's SNCs in vitro and to understand the expression characteristics of surface antigens hyperpolarization activated cyclic nucleotide gated cation channel 4 (HCN4) and connexin 45 (Cx45) on SNCs. Methods: The SNCs were isolated from sinus node tissues removed from neonatal rats by trypsin and purified cultured with differential attachment and 5′-bromodeoxyuridine (BrdU) treatment. Results: Three different types of cells were observed among the purified cultured SNCs: spindle, triangular and irregular cells. The spindle cells took up the greatest proportion, had the fastest beats, and had less developed organelle and scarce muscular fibrils. Immunofluorescence staining was positive against HCN4 and Cx45 on the spindle cells. Small amounts of HCN4 was observed on triangular cells. Conclusion: Circled digit oneIsolation by trypsin combined with differential attachment and BrdU treatment is a reliable approach to culturing sinoatrial node cells. Circled digit twoThe spindle cells with the fastest beats and positive expressions of HCN4 and Cx45 may be the sinus node pacemaker cells.