From the picture it can be seen that Bicarbonate is secreted into lumen of duct of salivary glands by exchanging Cl- ions.
So if flow rate of saliva is increased then its obvious that less Cl- is taken in the cells and less bicarbonate is secreted out.
At high flow rates, there is less time for reabsorption and secretion, and therefore the saliva is most like the initial secretion by the acinar cells. Thus, with the increase in flow rate the concentration of ions changes2
But it is also said that when flow rate increases the bicarbonate concentration also increases and when flow rate decreases bicarbonate concentration also decreases.
Doesn't this contradict the former fact?