Neuroscienee Letters, 97 (1989) 97 102 97 Elsevier Scientific Publishers Ireland Ltd. NSLO5854 Multiple voltage-sensitive K + channels regulate dendritic excitability in cerebellar Purkinje neurons D.L. Gruol l, V.E. Dionne 2 and A.J. Yool 1 IDivision ¢!/Preelinieal Neuroscience and Endocrinology, Research Institute ¢~['Seripps Clinie, La Jolla, CA 92037 (U.S.A. ) and :Department ¢~fl Medicine, University of Cal(/brnia at San Diego, La Jolla, CA 92037 ( U.S.A. ) (Received 12 May 1988; Revised version received 27 September 1988; Accepted 3 October 1988) Key wordsv Dendrite; Voltage-sensitive conductance; Potassium channel; Purkinje neuron; Single-chan- nel recording Ionic conductances present in the dendritic region of the ccrebellar Purkinje neuron were studicd using thc single-channel and whole-cell recording methods. Several types of voltage-sensitive K* channels including a Ca" ~ activated K ~ channel werc found to be a prominent components of the dendritic mem- brane. All patches studied contained K + channel types and most patches contained more than one K ~ channel type. In cell attached recordings, K + channel activity was associated with the late phase of sponta- neous action potentials suggesting a functional relationship. These data demonstrate that voltage-sensitive ion channels contribute to dendritic excitability and suggest that the transduction and integration of synaptic signals may involve both active and passive ionic conductances. The dendrites of CNS neurons play a central role in the reception and processing of synaptic signals. Classically, dendrites have been modeled as chemically receptive, electrically passive elements that transduce, integrate and transmit synaptic signals according to principles established for electrical cables [14]. However, intracellular recordings from the dendritic region of the two CNS neuronal types, the cerebellar Purkinje neuron [6, 12] and the hippocampal pyramidal neuron [2, 15], revealed that active responses could be recorded in this cellular region, suggesting that voltage-sen- sitive conductances are present in the dendritic membrane. We have tested this possi- bility directly using single channel recordings from the dendritic region of cerebellar Purkinje neurons (PN) in culture. The cultures were prepared from the cortical region of embryonic rat cerebella according to methods developed in our laboratory [5]. We have previously shown that many of the physiological properties of the cultured PNs parallel properties de- scribed for PNs in vivo or in the slice preparation [5, 7, 8]. The dendritic structure Correspondence." D.L. Gruol, Division of Preclinical Neuroscience and Endocrinology, Research Institute of Scripps Clinic 10666 North Torrey Pines Road, La Jolla Pines Road, La Jolla, CA 92037, U.S.A. 0304-3940/89,$ 03.50 @ 1989 Elsevier Scientific Publishers Ireland Ltd.