Calcium-dependent after-potentials in visceral afferent neurones of the rabbit.

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Abstract
Intracellular recordings were made from neurons in nodose ganglia excised from rabbits. In C neurons, 1-60 action potentials were followed by an after-hyperpolarization with a peak amplitude of 16 mV and a time constant of decay ranging from 3-10 s. In A neurons, the action potentials were followed only by a brief (up to 50 ms) after-hyperpolarization. The after-hyperpolarization was associated with an increase in the membrane conductance to K ions; it reversed polarity at the K equilibrium potential. The increase in conductance following the action potentials was blocked by removal of Ca ions, or addition of Co to the extracellular solution. Intracellular injection of ethyleneglycol-bis(.beta.-aminoethylether)-N,N''-tetraacetic acid abolished the after-hyperpolarization; intracellular injection of Ca mimicked the after-hyperpolarization. Ca entry during the action potential leads to a long-lasting increase in K conductance in visceral afferent C neurons.