Laboratorio 1 Notes

Pagina 1

Calculate the permeability at rest for Potassium, Calcium and Sodium for a human ventricular cardiomyocite. To calculate the permeability of a single ion I am going to use the GHK equation. The it looks like that. Where F = 96485 C/M, R = 8.314 J/(MK), T say is 310 K and the valence Zk is 2 for Calcium, 1 for Potassium and 1 for Sodium. The concentrations are given as mol/cm3 and the voltage in Volts. This implies that the units of the current will be in A/cm2 and thus the permeability is expressed in cm/s. If we know the ion flux for a given ion, resting potential and ex/in concentrations, we can compute the current in that steady state conditions. PARAMETERS of the OHARA SIMULATION CaMK is related to the intracellular potential of calcium. Another parameter is cell geometry, which contains the length, the radius because it is simulated as a cylinder. Diff contains the currents inside the cells. Environments contains the integration time. Extracellular contains the concentrations. So now let’s consider our example. Consider that 1 millimolar is 10^-3 molar that is mole over liter and 1 liter is 1000 cubic centimeters. So in order to pass from millimolar to mole per cm3 you have to multiply per 10^-6. In the model we opened we have 1.8, 5.4 and 140 millimolar for Ca, K and Na respectively. ICab is the background Calcium current: The Ica that basically transport Ca ions, but their contribute one- by-one is small, so we group the together. ICaL is very important because this current is the one that is actually related to the release of calcium inside the cell, and it is responsible for the release of calcium that will trigger the muscle contraction. It has a major role not only for the action potential but also for the heart contraction. The other important parameter is…