Question

Here is a partial list of Candice’s blood work:

Test

Candice

Normal

Glucose, Serum (mg/dL)

82

65-99

Uric Acid, Serum (mg/dL)

4.2

2.5-7.1

Creatinine, Serum (mg/dL)

1.2

0.57-1.00

Sodium, Serum (mEq/L)

133

134-144

Potassium, Serum (mEq/L)

7.0

3.5-5.2

Chloride, Serum (mEq/L)

103

97-108

Calcium, Serum (mg/dL)

9.5

8.7-10.2

24. Use the Nernst equation (below) to calculate the equilibrium potential for potassium in a normal patient and in Candice; assume [K]in is 150 mEq/L in Candice and in normal patients, and [K]out is 4 mEq/L in normal patients.

E K+ (millivolts) = 61 log10 ([K+ ] out /[K+ ] in)

25. If the resting membrane potential exhibits the same change as the equilibrium potential for potassium, predict how Candice’s ion imbalance will affect a cell’s resting membrane potential; would Candice’s resting membrane potential be hyperpolarized or depolarized?

Answer 1

Q24) K+ inside = 150 mEq/L

K+ outside for candice= 7 mEq/L

K+ outside for normal= 4 mEq/L

Using the formula,

E K+ (millivolts) = - 61 log10 ([K+ ] out /[K+ ] in)

E K+ for normal (millivolts) =- 61 log10 ([150 ] out /[4 ] in) = -61 X 1.57 = - 95.77 mEq/L.

E K+ For candice (millivolts) = - 61 log10 ([K+ ] out /[K+ ] in) = -61 Log10 (150/7) = -61 X 1.33= -81.13

Candice's resting membrane potential will move more towards depolarisation as the RMP is less negative than normal individual and hence it can be easily depolarised.