Resting Membrane Potentials

RMP	Tissue	Depolarization due to
-70	Most Cells	Na+
-90	Skeletal Muscle	Na+
-90	Ventricle	Na+
-90	Large Motor Spinal Neuron	Na+
-30 to -40	Smooth Muscle	Ca+
-30 to -40	SA node	Ca+

Increase K+ in ECF --- decreases RMP i.e -70 to -65 mV

Please note that here decrease is not taking negative sign into consideration.