Time-sharing contributions of A- and D-type K⁺ channels to the integration of high-frequency sequential excitatory post synaptic potentials at a model dendrite in rats

A- and D-type K⁺ channels (KA and KD channels) have unique physiological properties that play important roles in the integration of excitatory post synaptic potentials (EPSPs) in neuronal dendrites. These functions were analyzed using a computer program, NEURON, to simulate high- frequency sequential synaptic inputs, that can induce long-term potentiation (LTP). We paid close attention to the stability of the reduction of sequential EPSPs. When either KA or KD channels were included in models, the EPSP reduction ratios were less stable than containing both KA and KD channels. When both KA and KD channels were present in the model, the variance of EPSP reduction ratios was significantly smaller in comparison with that in the presence of either KA or KD channels alone. We thus concluded that the co-existence of KA and KD channels is necessary to produce stable EPSPs during the high-frequency synaptic stimulation necessary for induction of LTP. (C) 2000 Elsevier Science Ireland Ltd.