The electrical activity recorded from smooth muscle of the circular layer of the human stomach.

The membrane properties of circular muscles of 55 human stomachs were investigated by microelectrode and double sucrose gap methods. The membrane potential of the circular muscle of the corpus region was -57 mV and no regional difference was evident as compared with tissues from the antrum and cardia. The stomach muscle presented cable like properties, and the length constant measured in the corpus region was 1.34 mm. The circular muscle of all regions of the stomach exhibited slow waves. The amplitude and duration of slow waves varied markedly (the mean values were 18 mV and 6 s, respectively). The Q10 value for the slow wave was 2.4. The slow wave could be divided into two different components (first and second component) by application of electrical current or by using solutions with various ionic environments. Na ions had more effect on the spike component and Ca ions on the second component. The generation of the first component of the slow wave was blocked by either Na-free, K-free, Ca-free, or Cl-deficient solution but this component reappeared by application of outward current pulse, except in Cl-deficient solution. These results suggest that the generation of slow wave depends on more than one type of ion and that metabolic factors do indeed play a role. Membrane properties of the human stomach were compared with those of the guinea-pig stomach.