An in vitro micro-volume procedure for rapid measurement of erythrocytic hexose monophosphate shunt activity.

A radiometric micro-volume procedure for measurement of erythrocytic hexose monophosphate shunt (HMS) activity in intact cells in vitro is described. The procedure is rapid, allowing 200 individual HMS determinations in a single experiment of 5 hr duration. The procedure is reproducible, yielding HMS activity means insignificantly different (P greater than 0.05) between replicate experiments. A profile of sodium nitrite-induced HMS stimulation is reported: HMS was elevated 2-fold (P less than 0.001) between zero and 2.5 mM NaNO2; HMS elevation was more distinct (7-fold) between 2.5 and 5.0 mM NaNO2; maximum activity (22-fold) was observed between 10 and 20 mM NaNO2; greater than 20 mM NaNO2 caused significant (P less than 0.001) diminution of HMS; glucose carbon recycling through the HMS occurred only with greater than 2.5 mM NaNO2 where this process contributed less than or equal to 16% to total HMS activity.