FIGURE 3.

Regulation of proportional excretion of renal ammonia generated by acid-base conditions. Acute metabolic acidosis and alkalosis change the proportion of ammonia generated in the kidney that is excreted in the urine, where it contributes to net new bicarbonate generation, as opposed to systemic addition by transport into the renal veins, where it does not. During the chronic phase of metabolic acidosis, there is no further increase in the proportion of ammonia generated that is excreted in the urine; changes in net ammonia excretion are the result of increased net ammoniagenesis in chronic metabolic acidosis. [Data from Deferrari et al. (61).]