Spontaneous rhythmic activity in gastric smooth muscle is maintained by a complex network of smooth muscle cells (SMC), interstitial cells of Cajal (ICC) and a nerve plexus (NP). In rat gastric antrum a spontaneous activity of 3-5 contraction cycles per minute is regularly recorded. Acetylcholine, Substance P, Serotonin and Bradykinin stimulate gastric activity with small effect on the contraction frequency. Uncoupling between ICC and SMC was performed by Octanol application (about 0.03 vol %). A similar effect was achieved with a moderate temperature drop and spontaneous activity was inhibited by both treatments. Since the smooth muscle cell membrane acts as a "postsynaptic membrane" to integrate signals from ICC, gap junctions and ion channels we developed a method in which the single elements, leading to excitation or inhibition were displayed. Using this technique, acetylcholine acts on both sites (ICC and SMC) in comparable manner which was also true for Serotonin and Bradykinin. In contrast to that, the ICC was the main target for Substance P. This fact is important to understand composition and modulation of gastric rhythmic activity.