Relation between Cell-to-Cell Junctions and Electrical Activities in the Dog and Frog Stomach

Electrical activities and cell-to-cell junctions in dog and frog stomach muscle were investigated.In frog stomach no repetitive spike discharges (burst spikes) superimposed on a slow wave, similar to those recorded from dog stomach, could be recorded using microelectrodes, pressure electrodes and suction electrodes.In general, nexuses are absent in the longitudinal muscle layer of dog stomach and everywhere in frog stomach. Close apposition contacts are common in both muscle layers of canine and frog stomach. Thus, present findings indicate that electrical coupling in the frog stomach can occur without nexuses, and the distribution of the close apposition contacts can provide the primary structural basis for coupling of electrical control activity. Rapid electrically coordinated contraction is unlikely in the fundus of dog stomach and at any regions in frog stomach. Nexuses may be required to provide an invariable pathway of current flow and the mechanical connection between cells.