REN and pulmonary arterial hypertension: 1996). Although hANG and hRN mice show normal blood pressure because of species specificity in the reaction between angiotensinogen and renin, feto-placental human renin flows into maternal circulation and react with human angiotensinogen in PAH mice (Fukamizu et al. 1993; Takimoto et al. 1996). Consequently, a large amount of AngII is produced and PAH mice exhibit maternal hypertension, cardiac hypertrophy, proteinuria, and intrauterine growth retardation of embryos during late pregnancy (Takimoto et al. 1996; Saito et al. 2004).