Emerging Concepts in Ion Channel Biophysics

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Emerging Concepts in Ion Channel Biophysics Poster Abstracts
108
54-POS Board 54
Visualizing Calcium Nanodomains in Living Cells through Ion Channel Optical-
Recordings.
Jose P. Ocelotl-Oviedo1, Adán O. Guerrero-Cárdenas 2, Jose D. Martínez-Reyes3, Ángel G.
Velasco-Félix2, Juan García-Rincon2 , Carlos E. Batián-Eugenio4, Luis Vaca-Domínguez4,
Alberto Darszon1.
1Biotechnology Institute, Cuernavaca, Morelos, Cuernavaca, Mexico, 2National Advanced
Microscopy Laboratory, Cuernavaca, Morelos, Mexico, 3Genomics Science Centre, Cuernavaca,
Morelos, Mexico, 4Cellular Physiology Institute, Mexico City, Mexico.
Calcium plays a pivotal role in cell physiology as it acts as a second messenger in many
signaling processes. Calcium signaling is tightly regulated through the generation of highly
localized signals. Single channel activity has been widely studied using patch clamp techniques
and a variety of single Ca2+ channel activities studied. Nevertheless, cells with complex
morphologies and Ca2+ channels with very small single channel conductances (i.e. SOCs) still
present a challenge for patch champ techniques. We present a non-invasive methodology, based
on the optical recordings of fluorescent calcium probes using total internal reflexion microscopy
which allows studying single Ca 2+ channel activity in living cells. Furthermore, we extended the
theory of non-stationary noise analysis of macroscopic currents, developed by (Sigworth. J.
Physiol. 307:97. 1980), to provide reliable estimates of the number of ion channels in optical
patch clamp recordings. Theoretical (Markov Chain Models of single channel activity) and
experimental studies of optical path clamp recordings of Ca2+ channels (genetically encoded
P2X4 fluorescent channels) are presented as case studies.
Acknowledgements: This work was supported by CONACyT and PAPIIT/UNAM to LV, AD
and AG.
The results will be discussed.