Objective   To observe the direct influence of CO

2

pnemumoperitoneum on the growth and metastasis of seeded SGC-7901 cells in nude mice

and to investigate its effect of CO

2

pnemumoperitoneum on the expressions of heparanase (HPA) and vascular endothelial growth factor (VEGF) in the tissue of tumor.    Methods   Totally 27 nude mice were randomly divided into 3 groups (9 in each group)

2 groups of CO

2

pnemumoperitoneum (5 or 8 mmHg CO

2

) and control group. After SGC-7901 cells suspension (2×10

6

) were injected into peritoneal cavity of all nude mice

the CO

2

pnemumoperitoneum pressure at 5 or 8 mmHg was established for 1 h. The control group also underwent a midline incision

which was closed 1 h later as in CO

2

pnemumoperitoneum groups. Four weeks later

all nude mice were killed

then the tumorigenesis

the total weight

mean max diameters of tumor mass in the peritoneal cavity were observed and recorded. The expressions of HPA and VEGF in the xenograft were measured by immunohistochemical method.    Results   There was no significant difference in the number of abdominal cavity nodules

the total weight and the mean max diameters of each group (P0.05). The expression of the HPA and the in gastric cancer tissues showed no significantly difference in each subgroup (P0.05).    Conclusion   CO

2

pnemumoperitoneum does not accelerate the the growth and invasion of SGC-7901 cells in vivo

and the expression of the HPA and the VEGF in the tumor mass.