G_CaL vs. k_naca

Eli CohenJosue Cordones

Sviatoslav KendallCMACS Workshop 2013

Knaca: Sodium/Calcium Exchanger

• Expels one Calcium ion (Ca2+) from the cell by pulling in three Sodium ions (Na+)

• Net effect: inside of the cell becomes more positive with each turn

• Restores calcium concentration after action potential

Gcal: Maximal Calcium Conductance

• Directly proportional to L-type Calcium current (Ical)

• [insert equation]

• Affects slow, inward current that serves to sustain action potential

Predictions:

• High Gcal values should give long action potentials

• Low Knaca values should also give long action potentials

• Longest action potentials should be seen with high Gcal and low Knaca

Methods:

Methods…

Results

• Spiral seemed to always migrate leftward• No apparent trend in either the paths or the

spirals. In all cases if undisturbed the spiral would eventually migrate off the screen.

• No apparent difference between Day 1 and Day 2

Day 1 Paths

Day 2 Spirals

Comparison of Close-upsDay 1 Day 2

Action Potential at the Extremes

(0.2, 1.8)

(0.2, 0.2)

(1.8, 1.8)

(1.8, 0.2)

Insights

• Changing parameters may have affected the path of the spiral tip.

• Maybe not…could be that it’s not the values of the parameters that affects the path, rather the position of spiral when changing values serves as initial conditions for the new set of parameters.

• But…if that’s true, that means the new set of parameters does have some effect on the spiral, but we couldn’t find a trend.

Undisturbed at (1.0, 1.0)

Action Potential at the Extremes

(0.2, 1.8)

(0.2, 0.2)

(1.8, 1.8)

(1.8, 0.2)

Future…

Acknowledgements (check spelling)

• Flavio Fenton, • Robert Gilmour,• Bard Ermentrout, • Nancy Griffeth for putting it all together • Aaron Wolinetz for logistical/moral support

(food/jokes)• Chuck, Rachel & Daniel for being there• Peter for his programming prowess