Figure 6. Sildenafil enhancement of oxytocin release from isolated posterior pituitary.

Basal and evoked release were measured in two rounds as described in Methods. A, in the control experiment basal and evoked release did not change between the two rounds. Electrical stimulation of the axon bundle (5 trains of 10 s and 25 Hz) increased release ∼5-fold over the basal level. B, adding sildenafil (15 μm) to the bathing solution after the first round increased the evoked release in the second round 3-fold. C, adding sildenafil with 7-NI (200 μm) left the release in the 2nd round identical to that in the 1st (as in the control). D, bar graph illustrating the effects of sildenafil and sildenafil + 7-NI on basal and evoked release. For control, n= 5; for sildenafil, n= 6, for sildenafil + 7-NI, n= 6. *Indicates P < 0.05 by the t test.