160 likes | 313 Views
How do Calcium and Potassium conductance affect atrial fibrillation?. Fluctus (Group 3) Maisam T. Begum Joshua Finer Peter Valdez. Over 2.2 million people in the US have atrial fibrillation (8 - 9% of people over 80). Blood clots can form, leading to a stroke.
E N D
How do Calcium and Potassium conductance affect atrial fibrillation? Fluctus(Group 3) Maisam T. Begum Joshua Finer Peter Valdez
Over 2.2 million people in the US have atrial fibrillation (8 - 9% of people over 80). Blood clots can form, leading to a stroke. Some symptoms include irregular heart beats, chest pain, and shortness of breath. Still not well understood. Atrial Fibrillation
TNNP Model • Based on experimental data. • Attempts to more accurately represent the action potential than other models by including more than a minimal number of parameters. • Computationally tractable (especially with progress in GPUs).
Calcium conductance: GCaL Potassium conductance: GKs Conductance
Generates inward Calcium current (ICaL). Depolarizes cell. L Type Calcium Channels Potassium Channels • Generates outward Potassium current. • Hyperpolarizes cell. • Includes slow outward Potassium current (IKs).
http://www.nature.com/nature/journal/v451/n7181/fig_tab/nature06799_F2.htmlhttp://www.nature.com/nature/journal/v451/n7181/fig_tab/nature06799_F2.html
http://www.cvpharmacology.com/antiarrhy/cardiac_action_potentials.htmhttp://www.cvpharmacology.com/antiarrhy/cardiac_action_potentials.htm
Increasing GCaL would increase ICaL and make the spiral wave thicker. Increasing GKs would increase IKs and make the spiral wave thinner. Hypothesis
Parameter Range: 25% - 185% Parameter Increment: 20% Methods GKs GCal
Loop & Hook GCaL= 65% GKs= 145%
Drift GCaL= 125% GKs= 85%
Spin GCaL= 65% GKs= 65%
Our hypothesis was wrong since many of the spiral waves looked very similar. It is difficult to draw a conclusion since many of the spirals looked very similar. We think there might be a well-defined pattern of the spiral wave tip path. Discussion/Conclusion
Repeat simulations (with slight variations). Change more than 2 parameters at a time. Include the graphs of how membrane potential changes over time. Look at single individual periods. Future Work
A special thanks to Dr. Griffeth, Dr. Fenton, Aron, Chuck, Rachel, Dan and CMACS. Acknowledgments