Figure 5. Methylamine (MA) hastens and propionic acid inhibits the enhancing effect of glucose on sperm beat frequency.

A, Sperm were exposed for 100 s to 10 mM lactate before being stimulated for 150 s with 5 mM glucose and 15 mM MA. Subsequently, cells were allowed to recover for 200 s in lactate-containing buffer. B, Cells were treated for 500 s with 5 mM glucose of which propionate was additionally present during 200 s as indicated. The plots of A and B show mean values of 25–33 cells of 3 animals. Mean slopes (in a and b) were analyzed as described in the previous figure legend. C, After primary perifusion with 10 mM lactate, sperm were perifused for 30 min with buffer HS containing 5 mM glucose of which 15 mM MA (black plot) or 15 mM propionate (gray plot) were concurrently present first 10 min (t  = 0 min to t = 10 min). Significant changes were analyzed relating to t  = 0 min and apparent at t ≥5 min (co-application of MA) and at t ≥15 min (after removal propionate) with ***p<0.001. Shown are mean values±s.e. of 40 cells of 3 animals.