 Cortisol's only direct effect on the hydrogen-ion excretion of the kidneys is to stimulate the excretion of ammonium ions by deactivating the renal glutaminase enzyme.Cortisol works with adrenaline (epinephrine) to create memories of short-term emotional events; this is the proposed mechanism for storage of flash bulb memories, and may originate as a means to remember what to avoid in the future.However, long-term exposure to cortisol damages cells in the hippocampus; this damage results in impaired learning.