| Abstract: | Continuous rhythmic contractions were observed in longitudinal muscle strips of fundus obtained from the chronically vagotomized rat stomach. These vagotomy-induced rhythmic contractions (VRC) were not blocked either by tetrodotoxin (3 x 10(-6) M) or atropine (3 x 10(-7) M), indicating that the VRC was myogenic in origin. It was also found that the VRC had the following characteristics. 1) The VRC blocked either by 10(-5) M D600 or by Ca2+ deprivation from the medium. 2) On replacement of Na+ with sucrose or of K+ with Na+, the tone of fundus strips was concomitantly elevated with the cessation of the VRC. 3) 10(-5) M ouabain blocked the VRC. 4) The VRC was blocked by cooling. 5) The VRC disappeared under anoxic conditions. Based on these results possible mechanisms of the VRC are discussed in relation to an energy dependent activity of the cell membrane. |
