Scenario (hypothetical)): You participate in a research project with neurons in cell culture that are an established, we

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: Scenario Hypothetical You Participate In A Research Project With Neurons In Cell Culture That Are An Established We 1 (51.85 KiB) Viewed 11 times

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Scenario (hypothetical)): You participate in a research project with neurons in cell culture that are an established, well studied cell line. Intracellular and extracellular ion environments are known and controlled. All key parameters are listed in the table. Experiments are carried out at 30 °C. To prepare for -hypothetical- experiments in Assignment #3 you must Calculate Equilibrium Potentials E for all ion species (Na*, K*, Ca²+, Mg²+, CI) listed in the table below using the Nernst Equation, as well as the resulting Membrane Resting Potential VM expected under those conditions using the Goldman-Hodgkin-Katz Equation (see Handouts #2 for information how to do this). In Assignment #3 the calculated numbers will be used to formulate a research hypothesis, i.e., to predict the expected outcome of planned experiments, and discuss possible reasons why predictions and experimental results are different. This is routine work when doing experimental research! Assignment #3 will become available on May 23rd after this Assignment #1 is completed and submitted!

lon Extracellular Concentration Intracellular Concentration Membrane Permeability P for the ion species X [X]o 280 mM [X]₁ Na 20 mM 10 K 10 mM 390 mM 100 Ca²+ 30 mM 0.1 mM Not significant Mg2+ 20 mM 0.2 mM Not significant CH 590 mM 60 mM 1 You are expected to calculate and submit results for: ENO, EK, Ecaz, EMg2+, Ec, and VM at a Temperature of 30 °C You must present your results in BOTH Volt (V) AND milli Volt (mv)! Make sure that correct prefixes (+ or -) and units are provided with the numbers and that it is clear what each number describes (e.g., ENa+ = x.xx V/ ENa+ = xxx mV, VM = y.yy V/VM = yyy mV)! Required equations and constants for calculations can be found in the Appendix at the end of this handout!

Appendix: Nernst Equation E- RT Goldman Equation: V In PK [Klo PN [Na 'lo+ Pat (CI]₁ PK (K + PN [Na] Pa [CI] . R= gas constant: 8.315 J/ºK mol T= temperature in K (K="C+273.15) F= Faraday constant: 96485 C/mol z valence (electrical charge) of ion species X (depending on ion species +1, -1, or +2) [X]o. [K]o. [Nalo. [Cl]o= "outside", extracellular concentration of an ion species [X] [K], [No] [C], "inside", intracellular concentration of an ion species P PNa Pa relative membrane permeability of respective ion species In natural logarithm (Do not use log-decadic logarithm-) Results obtained with the equations are in Volts (V)! 1 V 1000 mV (0.1 V = 100 mV)! To convert V to mV multiply by 1000x! When the number matches the unit, both describe the same result! Do not forget to list results with their correct units (V or mV) and correct polarity,+ or -as required (substantial difference if + or -, just think about +20 °C and -20 °C)! I recommend adding polarity to all results, even if + is technically not needed! PROVIDE YOUR RESULTS IN BOTH V (Volts) AND mV (milliVolts)! I recommend using a regular scientific calculator to solve the equations, not the ones on smart phones or in computer software! RT [Xo In zF