The electrical activity of the smooth-muscle cells of the intact fundus led off intracellularly by glass microelectrodes with a resistance of 30 to 50 M omega was characterized by slow sinusoidal waves with a frequency of 1 to 2 cpm and an amplitude of 5 to 8 mV. They preceded low-amplitude contractile waves. The membrane potential was 29 +/- 9.83 mV. The resection of 2/3 of the stomach resulted in an increase of the frequency of slow waves--about 4 cpm and of their amplitude--from 12 to 25 mV. The membrane potential became 41.25 +/- 10.59 mV. The slow waves of the fundus after resection had the shape of action potentials type plateau. The contractile waves had a high amplitude and occurred in the same rhythm. The smooth-muscle cells of the intact fundus responded to transmural stimulation mainly with a hyperpolarization, while the smooth-muscle cells of the fundus after resection of the stomach--with depolarization and contraction of the muscle strip. It is concluded that the functional loading leads to deep changes in the pattern of the electrical and contractile activities of the gastric remnant.