Activation of membrane skeleton-bound phosphofructokinase in erythrocytes induced by serotonin

We show here that serotonin, both in vivo and in vitro, induced a marked activation of phosphofructokinase, the rate-limiting enzyme in glycolysis, in the membrane-skeleton fraction from erythrocytes. Concomitantly, the hormone induced a striking increase in lactate content, reflecting stimulation of glycolysis. The enzyme's activity in the cytosolic (soluble) fraction remained unchanged. These results suggest a defense mechanism in the erythrocytes against the damaging effects of serotonin, whose concentration in plasma increases in many diseases and is implicated as playing an important role in circulation disturbances.