Fig. 5.

Localization of P/Q-type-only synapses on dendritic shafts and spines of hippocampal neurons. Following FM 1–43 dye experiments synapses in which release depended exclusively on P/Q-type channels were identified and located in the FM 1–43 dye images from before (Loading, upper panel) and during release (Release, upper panel) as well as in the corresponding phase contrast micrographs (lower panel). (A) Some of the synapses blocked by ω-agatoxin IVA (arrowheads) located on the dentritic shafts (arrow), a position typical for GABAergic synapses. (B) Synapses blocked by ω-agatoxin IVA that are positioned at a slight distance to the dendritic shaft (arrowheads). Magnification (lower panel, right) clearly shows such a synapse (arrowhead) terminating on the head of a dendritic spine (arrow), a position typical for glutamatergic synapses. Images were magnified using a bicubic interpolation to 400% and 1066% (magnified inset) of the original resolution. Bars, 5 μm and 1 μm (insets).