Multicore vesicles: hyperosmolarity and L-DOPA induce homotypic fusion of dense core vesicles.
OBJECTIVE
A fraction of vesicles in cells treated with hypertonic solution exhibit multiple dense cores and this is enhanced by treatment with L-3,4-dihydroxyphenylalanine (L-DOPA). These cells were examined to determine if the multicore vesicles are the product of endocytosis or homotypic fusion.


METHODS
Electron microscopy was used to determine the number of multicore vesicles and amperometry was used to examine if the multicore vesicles are a competent fraction of the readily releasable pool.


RESULTS
In this study, we observed that a substantial portion (15.3%) of large dense core vesicles in PC12 cells contained multiple cores in hypertonic saline loaded with L-DOPA, and amperometric measurements show a bimodal distribution of quantal sizes in treated cells.


CONCLUSIONS
The results suggest that the multicored vesicles are formed from homotypic fusion of LCDVs prior to exocytosis.
Sombers
Leslie A
LA
Department of Chemistry, The Pennsylvania State University, 104 Chemistry Research Building, University Park, PA 16802-6300, USA.
Maxson
Marc M
MM
Ewing
Andrew G
AG
D000818:Animals; D015259:Dopamine Agents / Q000494:pharmacology*; D005089:Exocytosis / Q000187:drug effects / Q000502:physiology; D007980:Levodopa / Q000494:pharmacology*; D008561:Membrane Fusion / Q000187:drug effects*; D046529:Microscopy, Electron, Transmission; D009474:Neurons / Q000187:drug effects* / Q000648:ultrastructure; D009994:Osmolar Concentration; D016716:PC12 Cells; D051381:Rats; D012462:Saline Solution, Hypertonic / Q000494:pharmacology; D022142:Secretory Vesicles / Q000187:drug effects* / Q000648:ultrastructure
D015259:Dopamine Agents; D012462:Saline Solution, Hypertonic; D007980:Levodopa