ISSN:
1573-4935
Schlagwort(e):
Electron microscopy
;
secretion
;
neuropeptides
;
exocytosis
;
endocytosis
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Biologie
,
Chemie und Pharmazie
Notizen:
Abstract Exo- and endocytotic processes induced by depolarization of isolated neurosecretory nerve terminals show a close temporal correlation, which suggests a short time of integration of the neurosecretory granule membrane with the plasma membrane. In order to determine minimal time requirements for exocytosis-coupled endocytosis to occur, we have analyzed by electron microscopy uptake of horserdish peroxidase (HRP) as a fluid phase marker at the onset of depolarization. We have applied rapid mixing and sampling (quenched flow) to assess events in subsecond time peroids after stimulation. A significant number of labelled endocytotic vacuoles was observed during the first second of depolarization. This number then further increased by a factor of about 2 (within 5 s) and 4 (within 50s). Thus, as for exocytosis, the rate of endocytosis decreased considerably during prolonged stimulation. These data indicate i) that a substantial proportion of secretory granules undergoes exocytosis very shortly after stimulation, and ii) that, following exocytosis, the minimal time required for consecutive membrane retrieval is in the sub-second range.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF01122037
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