The explanation from my friend:

[FONT='Calibri', 'sans-serif']"In acidosis the collecting will increase its secretion of H+. This will decrease the negative charge in the lumen (see figure on page 419) of the notes) and as a consequence decrease the secretion of K+. Thus in the initial stage of an acidosis the hyperkalemia is associated with a decrease secrtion of K+ which would aggravate the hyperkalemia. With a chronic acidosis there is a diuresis that originates at the level of the proximal tubule. This is thought to be due to the inhibition of the Na pump by the acidosis. The secretion of K into the colloecting duct is also flow dependent thus the diuresis reverses the situation and an elevated K secretion results.[/font]
[FONT='Calibri', 'sans-serif']Alkalosis is usually associated with a hypokalemia for several reasons. Acutely the potassium may enter the cell in exchange for H+ as stated in the Kaplan notes. This may be a significant contributor the the hypokalemia and there can be an increase in intracellular K+. However, overall there is a tendency for a loss of body K+ in an alkalosis maily because of the origin of the alkalosis. Major causes of alkalosis include:- vomiting, a fluid with a high conc. of K+; diuretics, which wash out K+; excess minerocorticoids which increase the secretion of K+. There is also an increased negative charge in the collecting duct due to the reduced H+ secretion which promotes secretion of K+. The overall loss of K+ long term is the reason that the intracellular level falls chronically."[/font]