| Comments |
P.57 right column bottom paragraph to p.58 left column top paragraph: "Most synapses rely on three vesicle pools: Elmqvist and Quastel cautiously noted that although 'the experimental results are fully compatible with the [pools] model, they cannot be said in any way to prove it' [ref 4]. Since then, other possible explanations, including changes in intracellular calcium concentration, partial release from fully filled vesicles, full release from partially filled vesicles and desensitization and/or saturation of postsynaptic receptors have been investigated, but were not found to fully explain the observed changes in release. Therefore, through a process of exclusion, the idea of distinct vesicle pools that possess different capacities for exocytosis has been strengthened. Although the terminology varies, most models (for example, Fig. 1a) agree that presynaptic nerve terminals contain an RRP [readily releasable pool], from which vesicles can be easily mobilized on stimulation, and a large 'reserve pool', from which vesicles are drawn more slowly, typically in response to intense or prolonged stimulation. A further distinction can be made, as not all 'non-RRP' vesicles are equally capable of being released. Therefore, three pools of vesicles have to be postulated [ref 6]. The second pool of vesicles is released more slowly than the RRP, and its release precedes reserve pool mobilization-for the purpose of this review [investigators] term this pool the recycling pool. One striking example of the release of three vesicle pools is shown in Fig. 1b. Here, three different kinetic phases can be observed: a rapid, almost instantaneous one, a more prolonged slower one and a long-lasting phase. The properties of the three pool types are summarized in Table 1." |