Decrease of Bicarbonate to compensate Respiratory alkalosis
Bicarbonate ion is amphiprotic, as you've recognized. It can react as both a Brønsted base and as a Brønsted acid in water solution:

As an acid:

$K_a = 4.8 * 10^{-11}$

$\ce{HOCO_2^- + H_2O &lt;=&gt; OH_3^+ + CO_3^{2-}}$

As a base:

$K_b = 2.1 * 10^{-4}$

$\ce{HOCO_2^- + H_2O &lt;=&gt; HO^- + H_2CO_3}$ (not really true carbonic acid). 

Through K value inspection, we can see that the bicarbonate ion preferentially reacts as a base in water solution. The magnitude of this difference is massive; $K_b$ is more than a million times greater than $K_a$. 

So by decreasing the concentration of bicarbonate ion, we can combat respiratory alkalosis.