Question

Scenario: You will participate in a research project that involves working with neurons that are kept in cell culture. These neurons are well established cell model and their intracellular and extracellular environments are known. Required parameters are listed in the table below. All your experiments will be carried out at 20 ?C.

Calculate equilibrium potentials E for all ion species listed in the table below, as well as the resulting membrane resting potential VM.

But some calculations first! Intracellular Concentration [XliN 30 mM 310 mM 0.02 mM 0.2 mM 65 mM Membrane Permeability P in resting neuron Extracellular Concentration [XlouT 220 mM 8 mM 7 mM lon 10 100 Not significant Not significant 0.1 2+ Ca 2+--110 mM CI 580 mM You are expected to calculate and hand in results for: EN Ca2+ EM g2+ CI- Make sure that correct prefixes (+ or-) and units are shown!

Answer 1

The equilibrium potential or Nernest potential is calculated using below formula 1X96485 310 1X96485 30 out = 0.02526 X-3.657 =-0.0923 V Eq = 0.02526 In [7.33] = 0.5029 V Z. in Where In 7.33= 1.991 Where In (8/310)--3.657 Where: R = the universal gas constant and is equal to 8.314 J.Kl.mol-1 T = the temperature in Kelvin (K) z valence of the ion F= Faraday's constant and is equal to 96485 C.mol-1 EMg2+ = 8:31 4X293.15 In { 101 } 2X96485 0.2 2X96485 0.02 = Equilibrium constant = 0.01263 X 3.912 = 0.0494 V = 0.01263 X 5.857= 0.0739 V Xout- concentration of the ionic species X in the extracellular fluid Jin- concentration of the ionic species X in the intracellular fluid. Where In 10/0.2- 3.912 Where In 7/0.02 5.857 Ecl-= 8.314X293.15 In Resting membrane potential is calculated Goldman-Hodgkin Katz equation 1 5801 65 1X96485 = 0.02526 X 2.188= 0.0552 V Where In 580/65= 2.188 VM0.0498 V