I was wondering since channels of body's cell membranes deal with potassium and sodium ions differently and considering the fact that potassium lowers blood pressure and sodium raises it :
What is the most expensive in energy for kidneys between having to excrete an excess of potassium and an excess of sodium, for a healthy person and without considering blood pressure? Which process is the longest?
I know that insulin tends to make kidneys reabsorb sodium but does glucose help the kidneys to get rid of the excess potassium in any way?
On long term, what is the most harmful for the kidneys' circulatory system considering blood pressure and in the case of a kidney failure? For tubules and nephrons?