Vesicle impact electrochemical cytometry compared to amperometric exocytosis measurements

Abstract

Three new tools are discussed for understanding chemical communication between cells and primarily to delve into the content and structure of nanometer transmitter vesicles. These are amperometric measurements of exocytosis, vesicle impact electrochemical cytometry, and intracellular vesicle impact electrochemical cytometry. These are combining in the end nanoscale mass spectrometry imaging to begin determination of vesicle structure. These methods have provided solid evidence for the concept of open and closed exocytosis leading to partial release of the vesicle content during normal exocytosis. They have also been used to discover cases where the fraction of transmitter released is not changed, and other cases where the vesicle transmitter fraction released is altered, as with zinc, thought to alter cognition. Overall, the combination of these methods is showing us details of vesicular processes that would not be measureable without these micro and nano electrochemical methods.

Single Synaptic Observation of Cholinergic Neurotransmission on Living Neurons: Concentration and Dynamics

“…Besides, the lower range of the total number of the molecules for doublets and multiplets are similar orders of magnitude to that of the singlets (Table 3B); this suggests the partial release occurrence (Fig. 2E), as proposed in recent studies 54–, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67 during the first peak or the first couple peaks for some of the doublets and multiplets, respectively.…”

Mass Spectrometric Imaging of Plasma Membrane Lipid Alteration Correlated with Amperometrically Measured Activity-Dependent Plasticity in Exocytosis

“…The stimulation-dependent decreases of PC and simultaneous increases of PE and PI levels are likely to facilitate, in some way, the stabilization of the fusion pore during exocytosis. Recently, many studies have suggested that exocytosis, particularly for release from LDCVs, can occur via a mode of partial or “subquantal” release instead of full release, meaning that fused vesicles are able to release only a fraction of the transmitter molecules stored in the vesicle, followed by closure of the fusion pore and a rapid endocytotic process [ 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 ]. The concept of partial release opens the probability for the cell to adjust the vesicular transmitter load, in addition to exocytotic release, and offers a versatile pathway for a biological system to respond to the rapid change of the surrounding environment.…”

Lipid Membrane Permeability of Synthetic Redox DMPC Liposomes Investigated by Single Electrochemical Collisions

“…Since electron transfer do not readily occur across a bilayer lipid membrane, the electrolysis of the liposome redox active content after collision and membrane rupture or opening at the electrode surface provides insights on the membrane permeation mechanism. [12][13][14]16,17 According to Ewing and co-workers, the so-called vesicle impact electrochemical amperometry is mainly driven by an electroporation process of the vesicle membrane on polarized carbon UMEs which leads to the vesicle rupture and the electrolysis of its content. [18][19][20][21] Vesicle membrane opening by electroporation is strongly dependent on lipid membrane properties, liposome content, vesicle size, temperature, electrode potential, the nature of the electrode and probably the concentration of redox species inside and outside the liposome.…”