Final answer:
The change in resting membrane potential of renal tubular epithelial cells from -60 mV to -50 mV could be caused by increased potassium ion permeability.
Step-by-step explanation:
The change in the resting membrane potential of renal tubular epithelial cells from -60 mV to -50 mV could be caused by increased potassium ion permeability.
When potassium ion permeability is increased, more potassium ions will flow out of the cell, resulting in a less negative membrane potential.
This change can occur due to the opening of potassium channels in the cell membrane, allowing potassium ions to move down their concentration gradient and repolarize the cell membrane.