A: Ion Channels and Resting Membrane Potential Table 1 below contains values for various intracellular concentrations, extracellular concentrations, and ion conductance information for a cardiac cell. Table 1: lon Extracellular (mM) Na* 284 K+ 4 CI Ca2+ 120 10 Intracellular (mM) Resting Conductance (mS/cm²) 15 0.001 300 0.1 20 0.01 0.0001 1 1. Calculate the Nernst potential (nearest mV) for each of the above four ions (Na*, K*, Cl, Ca²+) assuming a temperature of 27 °C. Please show all work. (Possibly useful constants: R = 8.314 J K 1 mol‍¹; F = 9.65 x 104 C mol¹; J=Joule; K=Kelvin; C=Coulomb) 2. What is the resting potential (nearest mV) across the membrane using the Nernst potentials calculated in part 1 and the given conductance? (Note, please use the Nernst potentials rounded to nearest mV calculated in part 1 and show all work). Which ion's conductance dominates resting membrane potential and state the reasoning you used. (one or sentences)? 3. We apply a voltage clamp at +30 mV. Give the expected current and direction (across the membrane) for each of the 4 ions. Show your work; include units in your answer. Again, please use the rounded values calculated in part 1. After > a century of ion channel pharmacology, which general technique(s) would you use to test your expectation about the amplitude and direction of the 4 individual currents?

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A: Ion Channels and Resting Membrane Potential
Table 1 below contains values for various intracellular concentrations, extracellular
concentrations, and ion conductance information for a cardiac cell.
Table 1:
lon
Extracellular (mM)
Na*
284
K+
4
CI
Ca2+
120
10
Intracellular (mM)
Resting Conductance
(mS/cm²)
15
0.001
300
0.1
20
0.01
0.0001
1
1. Calculate the Nernst potential (nearest mV) for each of the above four ions (Na*, K*, Cl, Ca²+)
assuming a temperature of 27 °C. Please show all work.
(Possibly useful constants: R = 8.314 J K 1 mol‍¹; F = 9.65 x 104 C mol¹; J=Joule; K=Kelvin;
C=Coulomb)
2. What is the resting potential (nearest mV) across the membrane using the Nernst potentials
calculated in part 1 and the given conductance? (Note, please use the Nernst potentials
rounded to nearest mV calculated in part 1 and show all work). Which ion's conductance
dominates resting membrane potential and state the reasoning you used. (one or sentences)?
3. We apply a voltage clamp at +30 mV.
Give the expected current and direction (across the membrane) for each of the 4 ions.
Show your work; include units in your answer. Again, please use the rounded values calculated
in part 1.
After > a century of ion channel pharmacology, which general technique(s) would you use to
test your expectation about the amplitude and direction of the 4 individual currents?
Transcribed Image Text:A: Ion Channels and Resting Membrane Potential Table 1 below contains values for various intracellular concentrations, extracellular concentrations, and ion conductance information for a cardiac cell. Table 1: lon Extracellular (mM) Na* 284 K+ 4 CI Ca2+ 120 10 Intracellular (mM) Resting Conductance (mS/cm²) 15 0.001 300 0.1 20 0.01 0.0001 1 1. Calculate the Nernst potential (nearest mV) for each of the above four ions (Na*, K*, Cl, Ca²+) assuming a temperature of 27 °C. Please show all work. (Possibly useful constants: R = 8.314 J K 1 mol‍¹; F = 9.65 x 104 C mol¹; J=Joule; K=Kelvin; C=Coulomb) 2. What is the resting potential (nearest mV) across the membrane using the Nernst potentials calculated in part 1 and the given conductance? (Note, please use the Nernst potentials rounded to nearest mV calculated in part 1 and show all work). Which ion's conductance dominates resting membrane potential and state the reasoning you used. (one or sentences)? 3. We apply a voltage clamp at +30 mV. Give the expected current and direction (across the membrane) for each of the 4 ions. Show your work; include units in your answer. Again, please use the rounded values calculated in part 1. After > a century of ion channel pharmacology, which general technique(s) would you use to test your expectation about the amplitude and direction of the 4 individual currents?
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