Regulation of exocytosis in chromaffin cells by trans-insertion of lysophosphatidylcholine and arachidonic acid into the outer leaflet of the cell membrane.
Vesicular exocytosis is an important complex process in the communication between cells in organisms. It controls the release of chemical and biochemical messengers stored in an emitting cell. In this report, exocytosis is studied amperometrically (at carbon fiber ultramicroelectrodes) at adrenal chromaffin cells, which release catecholamines after appropriate stimulation, while testing the effects due to trans-insertion of two exogenous compounds (lysophosphatidylcholine (LPC) and arachidonic acid (AA)) on the kinetics of exocytotic events. Amperometric analyses showed that, under the present conditions (short incubation times and micromolar LPC or AA solutions), LPC favors catecholamine release (rate, event frequency, charge released) while AA disfavors the exocytotic processes. The observed kinetic features are rationalized quantitatively by considering a stalk model, for the fusion pore formation, and the physical constraints applied to the cell membrane by the presence of small fractions of LPC and AA diluted in its external leaflet (trans-insertion). We also observed that the detected amount of neurotransmitters in the presence of LPC was larger than under control conditions, while the opposite trend is observed with AA.
Amatore
Christian
C
Ecole Normale Supérieure, Département de Chimie, UMR CNRS-ENS-UPMC 8640 PASTEUR, 24 rue Lhomond, 75231 Paris Cedex 05, France. christian.amatore@ens.fr
Arbault
Stéphane
S
Bouret
Yann
Y
Guille
Manon
M
Lemaître
Frédéric
F
Verchier
Yann
Y
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D016718:Arachidonic Acid / Q000737:chemistry / Q000378:metabolism* / Q000493:pharmacokinetics; D002395:Catecholamines / Q000378:metabolism; D002417:Cattle; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism*; D002478:Cells, Cultured; D019439:Chromaffin Cells / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D005089:Exocytosis / Q000187:drug effects / Q000502:physiology*; D008244:Lysophosphatidylcholines / Q000737:chemistry / Q000378:metabolism* / Q000493:pharmacokinetics; D008839:Microelectrodes; D008954:Models, Biological; D015394:Molecular Structure; D013268:Stimulation, Chemical
D002395:Catecholamines; D008244:Lysophosphatidylcholines; D016718:Arachidonic Acid