A proposed relationship between vasopressinase altered vasopressin and preeclampsia.

Preeclampsia is characterized by increased vascular sensitivity to Angiotensin II, endothelial damage, and arteriolar spasm. We hypothesize that these events may be initiated by stimulation of V1 receptors. V1 receptors are normally activated by vasopressin. However, V1 receptors may be activated by the nonapeptide formed when vasopressin is metabolized by the placental enzyme--vasopressinase. This enzyme, found only in humans, cleaves the ring structure of vasopressin, but leaves the N-terminal end, the locus of pressor activity, intact. The resulting molecule, vasopressinase altered vasopressin (VAV), may be present in greater concentration in preeclamptic women and over the months of the second trimester initiate the cascade of pathophysiologic changes resulting in toxemia.