Question

In some tissues, such as skeletal muscle, there are non-specific, cation channels that allow both Na+ and K+ to pass when the channel is open. What is the equilibrium potential of for this channel in millivolts (mV)? The temperature is 37 °C. The extracellular Na+ concentration is 145 mM and the intracellular Na+ concentration is 15 mM. The extracellular K+ concentration is 5 mM and the intracellular K+ concentration is 150 mM. Assume that the channel is exactly equally permeable to both Na+ and K+.

Vm = 61.5 log (Pkout +Pnaout + Pclin / Pkin+Pnain+Pclout)

Answer 1

The equilibrium potential for a non-specific cation channel in skeletal muscle can be calculated using the Nernst equation.

Step-by-step explanation:

The equilibrium potential for a non-specific cation channel in skeletal muscle can be calculated using the Nernst equation.

The Nernst equation is given by: E = (RT/zF) ln (K+out/K+in)

Where:

• E is the equilibrium potential
• R is the ideal gas constant (8.314 J/(mol·K))
• T is the temperature in Kelvin (37 + 273 = 310 K)
• z is the charge of the ion (+1 for both Na+ and K+)
• F is the Faraday constant (96485 C/mol)

Using the given concentrations of Na+ and K+, we can plug in the values and solve for E.

For Na+: E = (8.314 * 310 / (1 * 96485)) * ln (145 / 15) = -78.4 mV

For K+: E = (8.314 * 310 / (1 * 96485)) * ln (5 / 150) = -90.3 mV

Since the channel is equally permeable to Na+ and K+, the equilibrium potential will be the average of the two: E = (-78.4 + -90.3) / 2 = -84.4 mV.