An increase in external K+  concentration:
With hyperkalemia, membrane voltage is depolarized gradually. Depolarization of membrane voltage means decrease in RMP. Remember, a decrease in the membrane potential (RMP) means that the voltage has moved closer to ground (0 mv) or become more positive.
Decrease RMP
Increase RMP by  –10 mv for each 10 mEq/L increase in K+
No change
Increase RMP by –20 mv for each 10 meq/L increase in K+