Electrocardiogram results show a shortened QT interval and an increase in the P-R interval (i.e., decreased duration of action potential and decreased conduction velocity). Laboratory results indicate that his serum potassium level has increased to a value of 6.5 mEq/L (normal: 3.5 to 5.0 mEq/L). This increase in serum potassium causes which of the following?
A. A decreased net driving force for potassium from cells
B. Decreased intracellular potassium concentration
C. Hyperpolarization of the resting membrane potential
D. More negative Nernst potential for potassium
E. More negative resting membrane potential