Can erythrocytes Function without plasma?
Erythrocytes need more than just glucose in order to function and, they also need a extracelullar medium who shares the same osmolarity, so placing your red blood cells into a medium that solely has glucose will be problematic. If you solely want to evaluate the lactic fermentation carried out by erythrocytes on a short period of time, then you can add the blood plasm on your centrifuge tube (which will be in the superior layer) to the newly separated erythrocyte fraction. This way, we make sure your extracelullar medium not only has every metabolite needed, but is also isotonic with respect to your erythrocytes. If you're planning on evaluating this pathway for a considerable amount of time (days, perhaps), then you, most likely, will have to prepare a solution with glucose that is isotonic with respect to your red blood cells.