Different effects of different phosphodiesterase type-5 inhibitors in pre-eclampsia

We aimed to determine the effects of sildenafil and vardenafil in human umbilical artery preparation taken from pre-eclamptic or normal pregnant women, and also to investigate the underlying mechanisms in these effects.

Fifteen pregnant women with pre-eclampsia and 15 healthy pregnant women were involved. Relaxation responses of sildenafil and vardenafil in the presence and absence of nitric oxide synthase inhibitor, N-[omega]-nitro-l-arginine methyl ester (l-NAME), and soluble guanylyl cyclase inhibitor, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), were compared between the pre-eclampsia group and the control group.

Sildenafil induced relaxation responses were significantly attenuated in the presence of pre-eclampsia, l-NAME and QDO. Similarly, pre-eclampsia, l-NAME or ODQ incubation also shifted vardenafil-induced relaxation responses rightward. However, in all set of experiments a maximal relaxation response was achieved by vardenafil unlike sildenafil. In conclusion vardenafil seems to relax human umbilical artery stronger than sildenafil in both pre-eclamptic and normal pregnancies.

These data indicate that vardenafil might affect vascular responsiveness of human umbilical artery through the involvement of NO/cGMP-dependent and independent pathways while sildenafil-induced responses were seemed to be completely NO/cGMP-dependent. Further investigations are needed to clarify the mechanisms.