Fig. 3. The anterior gastric receptor (AGR) shows spike frequency adaptation and sag potential. (A) Intracellular recording of AGR. AGR was depolarized with current injections. Bottom, +1 nA; middle, +3 nA; top trace, adaptation of AGR firing frequency during current injections. After an initial peak, firing frequencies dropped to constant value. (B) Current injections were used to hyperpolarize AGR to different membrane potentials. After an early hyperpolarized peak, the membrane potential decayed to a constant value (sag). After the end of the hyperpolarization, the membrane potential transiently overshot the resting potential and AGR firing frequencies increased (top trace).