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Show 17 college of engineering Sudden cardiac arrest kills 450,000 people in the United States every year, and occurs when there is a malfunction of electrical activity in the heart tissue, also known as arrhythmias. One of the factors affecting cardiac conduction is the expression and localization of gap-junctions, which link cardiac cells and allow for electrical propagation through the tissue. Cardiac gap junctions are mainly composed of connexin43 (Cx43) proteins. In this study, transgenic Cx43 knockout mice are used to investigate the effects of pressure and Cx43 expression on conduction velocity. The amount of extracellular space is being quantified with immunohistochemistry techniques to determine if pressure and Cx43 expression cause a disruption of fluid balance and are related to edema. The results from these experiments will help clarify the mechanisms by which electrical activity in the heart malfunctions, as well as how these mechanisms relate to each other. Currently, equal numbers of wildtype and heterozygous mouse hearts have been isolated and perfused with a Tyrode or Krebs solution before being fixed with formalin and stored in ethanol. Additional hearts were fixed without being perfused to compare the perfused hearts to control conditions (n = 4 for each condition and solution). After immunohistochemical staining is complete for these trials, pressure will be increased during perfusion and the outer surface of the heart will be optically mapped before the tissue is fixed. Conduction velocity will be calculated and the amount of extracellular space, along with Cx43 ex-pression, will be determined. It is expected that an increase in pressure leads to slower conduction velocity, possibly as a result of increased extracellular space. Additionally, it is also anticipated that reduced Cx43 expression will exacerbate the observed results. By establishing how these factors are related, we will have a better understanding of the mechanisms associated with arrhythmias and sudden cardiac arrest. THE EFFECTS OF PRESSURE CHANGES ON CARDIAC CONDUCTION AND EDEMA IN CONNEXIN43 KNOCKOUT MICE Katie Sciuto (Steven Poelzing) Department of Biomedical Engineering University of Utah UNDERGRADUATE RESEARCH ABSTRACTS Steven Poelzing Katie Sciuto |
