Bicarbonate

Do some reading regarding acid and base balance. Specifically regarding Hydrogen and potassium. I think you will find an answer then.

it has to do with the transport of hydrogen vs transport of potassium across the cell membrane. i'm not 100% sure but i think for every .1 change in ph there is a .6 change in k. and it's inversely proportionate.

hydrogen and potassium are both positively charged ions. There is an electrical gradiant just like others like hydrostatic and so on. Bicarb sucks up the H ions which is why its given for acidosis. As the H ions are bound by the bicarb this changes the electrical gradient to more negative in the blood, which draws the K ions out of the cells to acheive electrical homeostasis. This raises serum K, which can lead to hyperkalemia=bad. Hope that's clear, I might have confused myself...

the above sounds pretty correct. Another aspect to consider is that using bicarb for pH control only achieves a temporary effect. The hydrogen that is buffered by bicarbonate is expressed as CO2, so unless they can blow it all off, the pH will rise again.