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Compound exocytosis in pituitary cells
Nina Vardjan1, Jernej Jorgacevski, Matjaz Stenovec
1Celica Biomedical Center, Ljubljana, Slovenia.
Annals of the New York Academy of Sciences
|January 24, 2009
Summary
Compound exocytosis in pituitary lactotrophs involves repetitive, transient fusion events. Stimulation enhances these compound exocytotic events, improving hormone secretion efficiency.
Area of Science:
- Cell Biology
- Neuroendocrinology
Background:
- Exocytosis, the process of neurotransmitter and hormone release, involves vesicle fusion with the plasma membrane.
- Previous studies showed spontaneous and stimulated exocytosis in pituitary lactotrophs are transient and repetitive.
- The nature of compound vesicle-to-vesicle exocytosis in these cells remained unclear.
Purpose of the Study:
- To investigate compound exocytotic events in both resting and stimulated pituitary lactotrophs.
- To characterize the mechanisms underlying vesicle-to-vesicle fusion during exocytosis.
Main Methods:
- Utilized optical and cell-attached patch-clamp capacitance measurements.
- Analyzed synaptopHluorin fluorescence and membrane capacitance signals for compound exocytotic events.
- Characterized events based on multiple-amplitude on-steps and off-steps.
Main Results:
- Identified elementary compound exocytotic events with multiple-amplitude on-steps, indicating multivesicular or sequential exocytosis.
- Observed repetitive, transient fusion pore openings in over 90% of recordings.
- Found a 33% increase in compound exocytotic events upon stimulation.
Conclusions:
- Compound exocytosis in pituitary lactotrophs is characterized by repetitive, transient fusion events.
- These repetitive interactions may facilitate vesicle-to-vesicle fusion through protein diffusion.
- Stimulation enhances compound exocytosis, correlating with increased hormone secretion efficiency.
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