LOW-THRESHOLD CALCIUM CURRENT IN DENDRITES OF THE ADULT-RAT HIPPOCAMPUS

The patch-clamp technique was employed in hippocampal slices to examine the characteristics of a low-threshold Ca current in adult CA1 pyramidal neurons. We found that adult CA1 pyramidal neurons possess a distinct transient low-threshold Ca current, located predominantly in the distal dendrites. Surgical cuts that separated the dendrites from the soma and left a dendritic length of 150 mu m, completely abolished the low-threshold Ca current while a transient K current persisted even in cells with dendrites as short as 50 mu m. The transient low-threshold Ca current in dendrites may represent a voltage-dependent Ca entry pathway which contributes to the regulation of cellular excitability, plasticity and pathology.