Figure 1.

A single AP can evoke three types of AHP in nodose neurons. (Top) A neuron with a single-component afterpotential lasting ≈30 ms. This AHP is designated AHP_fast. All neurons have this short duration afterpotential. (Middle) Example of a neuron with two afterpotentials, an AHP_fast followed by a longer lasting afterpotential (≈300 ms), the AHP_medium. In approximately half of the neurons, the AHP_medium is Ca²⁺-dependent. (Bottom) In a subset of C fiber type nodose neurons, a slowly developing (hundreds of ms) and long-lasting (2–15 s) afterpotential is observed. This slow afterpotential (AHP_slow) is always Ca²⁺-dependent. Intracellular recordings were obtained at room temperature from adult neurons isolated from rabbit nodose ganglia. The values near the horizontal lines are resting membrane potentials. The calibration in the Top also applies to the Middle. Similar results have been recorded in guinea pig and ferret nodose neurons.