We also showed that IUGR is associated with sex-specific alterations in the nitric oxide (NO)/cyclic GMP (cGMP)-mediated relaxing pathway in the HUV (5, 6): we observed a reduced relaxant response to the NO donor 2-(N,N-diethylamino)-diazenolate-2-oxide (DEA/NO) in the HUV of growth-restricted females compared to AGA newborns, despite a significant increase in soluble guanylyl cyclase (sGC) protein content and activity and some increase in cGMP-dependent protein kinase (PKG) protein amount compared to AGA HUV; in males, however, no significant difference was found between AGA and IUGR HUV. Here, PRKG1 is linked to fetal growth restriction.