NO production by cells harvested from the peritoneal cavity of EA-treated mice. BALB/c mice were treated with EA (15/30 Hz) at the Zusanli acupoint (ST36) for 20 min/d for 5 d (A and C) or 10 d (B). After the final EA session, the mice were euthanized and their peritoneal cells were harvested and cultured in the absence or presence of 1 μg/mL LPS (A and B) or 1 μg/mL LPS and 2 ng/mL IFNγ (C). After 48 h, the culture medium was harvested for nitrite measurement by the Griess assay. The data are represented as mean ± SD of the increase in nitrite production after LPS stimulation. The sham-treated mice received only needle insertion into a non-acupoint (gluteal muscle) without electrical stimulation. The data presented are representative of one of three independent experiments containing three mice in each group. *P < 0.05, significant difference between sham- and EA-treated mice under the same culture conditions by Student’s t-test; §P < 0.05, significant difference between cells from the same mouse group under different culture conditions by Student’s t-test.