Abstract
Most stored neuropeptide cannot be released from nerve terminals suggesting the existence of a refractory pool of dense core vesicles (DCVs). Past fluorescence photobleaching recovery, single particle tracking and release experiments suggested that the refractory neuropeptide pool corresponds to a distinct immobile fraction of cytoplasmic DCVs. However, tracking of hundreds of individual green fluorescent protein-labeled neuropeptidergic vesicles by wide-field or evanescent-wave microscopy shows that a separate immobile fraction is not evident. Instead, the DCV diffusion coefficient (D) distribution is unusually broad and asymmetric. Furthermore, the distribution shifts with a release facilitator. This unexpected variation, which could reflect heterogeneity among vesicles or in their medium, is shown to generate the appearance of a regulated refractory neuropeptide pool.
Original language | English (US) |
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Pages (from-to) | 4127-4134 |
Number of pages | 8 |
Journal | Biophysical Journal |
Volume | 84 |
Issue number | 6 |
DOIs | |
State | Published - Jun 1 2003 |
Externally published | Yes |
ASJC Scopus subject areas
- Biophysics