Christian Amatore, Director of the Chemistry Department of Ecole Normale Supérieure (ENS), Member of the French Académie des Sciences and Editor of the major international electrochemical journal (J. Electroanal. Chem.) will present the following seminar from the Pacific Rim Conference in Nanoscience (7-11 September 2004). The seminar will be available throughout September and October for viewing and discussion through the Nanotech Hub at http://nanotech.colayer.net/:
Ultramicroelectrodes for detection of chemical messengers
Living cells exchange information through the emission of chemical messengers. The importance of such messengers has been widely recognized by biologists. However what is less understood is how these chemical messengers are released by the cell in its outer-cytoplasmic fluids. This difficulty is easily understood when one becomes aware that most of these releases occur in the atto- or femtomole ranges which prevents the use of classical analytical methods. We wish to show here that ultramicroelectrodes may prove extremely useful for monitoring such events.
In this lecture we will be concerned by exocytosis of neurotransmitters although the same method may be applied to investigate oxidative stress cellular bursts. The target cells are chromaffin cells which are located above kidneys. These cells produce the initial adrenaline burst which induces fast body reactions; they are used in neurosciences as standard models for synaptic exocytosis by cathecolaminergic neurons. Prior to exocytosis, adrenaline is contained in highly concentrated solutions into a gel matrix packed into small vesicles dispersed in the cytoplasm near the cell membrane. Stimulation of the cell by divalent ions induces the fusion of the vesicles membranes with that of the cell and hence the release of the intravesicular content into the outer-cytoplasmic region.
Electrochemical data permit to describe the whole process of exocytosis with a precision that has never been achieved before by nano-optical or patch-clamp techniques. This enables to investigate kinetically these events and conclude upon the physicochemical origin of the individual factors which govern vesicular release. Based on this analysis, one may propose a first-time quantitative explanation for the release of chemical messengers by dense-core vesicles.
Some Relevant Key References
• C. Amatore. C.R. Acad. Sci. Paris, Ser. II b, 323 , 1996 , 757.
• E. L. Ciolkowski, K. M. Maness, P. S. Cahill, R. M. Wightman, D. H. Evans, B. Fosset, C. Amatore. Anal. Chem ., 66 , 1994 , 3611.
• T.J. Schroeder, J.A. Jankowski, K.T. Kawagoe, R.M. Wightman, C. Lefrou, C. Amatore. Anal. Chem , 64 , 1992 , 3077.
• T.J. Schroeder, R. Borges, K. Pihel, C. Amatore, R.M. Wightman. Biophys. J., 70 , 1996 , 1061.
• C. Amatore, Y. Bouret, L. Midrier. Chem. Eur. J. , 5 , 1999 , 1193.
• C. Amatore, Y. Bouret, E.R. Travis, R.M. Wightman. Biochim., 2000 , 82 , 481.
• C. Amatore, Y. Bouret, E.R. Travis, R.M. Wightman. Angew. Chem. , 112 , 2000 , 2028 . [ Angew. Chem. Int. Ed. , 39 , 2000 , 1952.]
• C. Amatore, S. Arbault, D. Bruce, P. de Oliveira, M. Erard M. Vuillaume. Faraday Discuss ., 116 , 2000 , 319.
• C. Amatore, S. Arbault, I. Bonifas, Y. Bouret, M. Erard, M. Guille. ChemPhysChem Eur. J ., 4 , 2003 , 147.
• L.A. Sombers, H.J. Hanchar, T.L. Colliver, N. Wittenberg , A. Cans, S. Arbault, C. Amatore, A. G. Ewing. J. Neurosciences , 24 , 2004 , 303 .
Barry Hardy
Douglas Connect
www.douglasconnect.com
Nanotechnology Hub: http://nanotech.colayer.net/
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