Brugia Malayi - Clark Science Center - Smith College

Investigation of a Molecular Mechanism for Anesthetic Preconditioning
Alexis Ziemba
Anesthetic preconditioning (AP) is a potential treatment for patients undergoing procedures that are accompanied by a high risk
for ischemic injury (e.g. perioperative stroke) and cannot be treated by anti-coagulants. AP is a phenomenon by which tissues are
pre-treated with clinical concentrations of a general anesthetic; this minor insult results in the upregulation of cellular protective
measures, which defend against greater insults such as ischemia. Our lab aims to discern the mechanisms by which this protection
occurs. We have proposed that exposure to the general anesthetic, isoflurane, increases the level of the signaling molecule nitric
oxide (NO) 2 , with astrocytes being the major producer of NO 1 . This triggers a downstream increase of free intracellular Zn 2+
(Figure 1). 5
To first confirm increases in NO following isoflurane exposure, isolated astrocytes were exposed to isoflurane in a dedicated
anesthetic chamber. The level of NO was measured six hours later using the Griess Reaction, a chemical analysis test. No
difference was seen in the level of NO following isoflurane exposure. As changes in the level of NO were shown to be timedependent
in the cell type, microglia, earlier time points will be tested in astrocytes.
To determine if there are increases in intracellular free Zn 2+ post-isoflurane exposure, dissociated brain suspensions were
incubated with a zinc-fluorescing dye, Zinpyr-1. The suspensions were then exposed to either isoflurane or NO generators, and
the fluorescence was measured before and after using spectrophotometric techniques. Unfortunately, no conclusions could be
made as both isoflurane and NO generators were demonstrated to affect Zinpyr-1 when no cells were present.
Further understanding of the mechanisms of AP could lead to more effective administration in a clinical setting. Future
studies will involve the study of metallothioneins (MT), zinc-binding proteins, which have been shown to be involved in the
protection. 4 MT wild type and knock out co-culturing experiments will be done to determine which cell types are involved in MTmediated
protection.
This work was continued from an honors thesis and was presented at the Beckman Symposium. (Supported by the Arnold
and Mabel Beckman Foundation)
Advisor: Adam Hall
References:
1
Bal-Price A and Brown GC (2001) J Neurosci 21:6480–6491.
2
Baumane L, Dzintate M, Zvejniece L, Meirena D, Lauberte L, Sile V, Kalvinsh I, Sjakste N (2002) Acta Anaesth Scand 46: 378–383.
3
Edmands SD (2009) Open Access Dissertations Paper 78:1-104.
4
Edmands SD and Hall AC (2009) Anesthesiology 110:538–47.
5
Stitt MS, Wasserloos KJ, Tang X, Liu X, Pitt BR, St. Croix CM (2005) Vasc Pharmacol 44:149-155.
2012
155