Double patch clamp reveals that transient fusion (kiss-and-run) is a major mechanism of secretion in calf adrenal chromaffin cells: high calcium shifts the mechanism from kiss-and-run to complete fusion.
Transient fusion ("kiss-and-run") is accepted as a mode of transmitter release both in central neurons and neuroendocrine cells, but the prevalence of this mechanism compared with full fusion is still in doubt. Using a novel double patch-clamp method (whole cell/cell attached), permitting the recording of unitary capacitance events while stimulating under a variety of conditions including action potentials, we show that transient fusion is the predominant (>90%) mode of secretion in calf adrenal chromaffin cells. Raising intracellular Ca2+ concentration ([Ca]i) from 10 to 200 microM increases the incidence of full fusion events at the expense of transient fusion. Blocking rapid endocytosis that normally terminates transient fusion events also promotes full fusion events. Thus, [Ca]i controls the transition between transient and full fusion, each of which is coupled to different modes of endocytosis.
Department of Pharmacology, Wayne State University School of Medicine, Detroit, Michigan 48201, USA. aelhamda@med.wayne.edu
Abdeladim
A
Elhamdani
Fouad
F
Azizi
Cristina R
CR
Artalejo
D000200:Action Potentials; D000313:Adrenal Medulla / Q000166:cytology* / Q000378:metabolism; D000818:Animals; D001464:Barium / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D002417:Cattle; D002462:Cell Membrane / Q000502:physiology* / Q000648:ultrastructure; D019439:Chromaffin Cells / Q000378:metabolism*; D025802:Electric Capacitance; D004558:Electric Stimulation; D004705:Endocytosis / Q000187:drug effects / Q000502:physiology; D005089:Exocytosis / Q000502:physiology*; D007425:Intracellular Membranes / Q000502:physiology* / Q000648:ultrastructure; D008561:Membrane Fusion / Q000502:physiology*; D008954:Models, Biological; D018408:Patch-Clamp Techniques / Q000379:methods*; D022142:Secretory Vesicles / Q000502:physiology* / Q000648:ultrastructure; D013324:Strontium / Q000494:pharmacology
D001464:Barium; D002118:Calcium; D013324:Strontium