| Cerebellum Purkinje GABA cell | Proximal equivalent dendrite | I Na,t | . | Simultaneous whole-cell recordings, made from the soma and dendrites rat brain slices, showed that AP evoked by either current pulses or synaptic stimulation of parallel or climbing fibers, always occurred first at the soma and decreased in amplitude with increasing distance into the dendrites. Simultaneous somatic and axonal recordings showed that these action potentials were initiated in the axon. Outside-out patches excised from the soma and dendrites up to about 100um revealed a channel density decreasing with distance from the soma. (Stuart G and Häusser M, 19942 ). However, in guinea pigs, a combination of high-speed imaging and simultaneous intracellular recordings showed that direct depolarization of the soma or dendrites never caused dendritic [Na+]i increases, suggesting that the climbing fiber-activated [Na+]i changes in the dendrites are due to Na+ entry through ligand-gated channels (Callaway JC and Ross WN, 1997 [guinea pig]1 ). NaV1.2 is substantially present throughout the dendrites, NaV1.1 is present in the soma and proximal dendrites, NaV1.6 is robustly present in cell bodies and dendrites, and NaV1.7 is absent from the cell (Ahn HS et al, 20113 ). (Schaller KL and Caldwell JH, 20034 ). (Dib-Hajj SD et al, 20105 ). |
