Background & Aims: Gastric electric stimulation (GES) has recently been explored as a therapeutic option for gastrointestinal motility disorders or obesity. The mechanism behind it is not fully elucidated. The aims of this study were to assess the effects of GES with different parameters on antral tone and to explore the involvement of the nitrergic pathway. Methods: Eight dogs equipped with a gastric cannula and one pair of serosal electrodes in the greater curvature 4 cm above the pylorus were studied on separated days. The study was composed of 7 randomized sessions in the fed state (control, GES with different parameters and GES plus neuronal nitric oxide synthase (nNOS) inhibitor). Each session included 3 consecutive 30-min periods (baseline, GES and recovery). GES was performed with long pulses or pulse trains. The antral volume was measured using an intragastric balloon connected with a barostat device. Behaviors of the dogs during each stimulation period were also noted. Results: 1) Postprandial antral tone was reduced with GES with all tested parameter settings, reflected as a significant and substantial increase in antral volume ranging from 179% to 309%. 2) The inhibitory effect of GES on antral tone was partially blocked (decreased by 39.5%) with an nNOS inhibitor. 3) Mild symptoms were induced with GES and found to be correlated with the GES-induced increase in antral volume. Conclusions: Retrograde GES with long pulses or pulse trains inhibits antral tone and this inhibitory effect is partially mediated via the nitrergic pathway. These results suggest that retrograde GES may have a therapeutic potential for obesity.