52 The role of methemoglobin reductase (CYB5R3) of erythrocytes in hypertension: From fetuses to pregnancy-induced hypertension

Introduction In pregnancy oxidative stress is increased, being the mechanisms associated to the regulation of redox system disrupted in preeclampsia. This pro-oxidative state in preeclampsia, starting at placental level, may be reflected in fetuses. Methemoglobin reductase (MHbR) is an erythrocyte antioxidant enzyme modulated by nitrites, blood pressure levels and age. Objectives To study if MHbR (CYB5R3) activity is related to preeclampsia and if this may be reflected on the fetus. Methods We studied MHbR activity in erythrocytes in one cohort of 141 pregnant women with 26.7 ± 5.5 years old, being 99 (70.2%) normotensive (NT)-pregnant women and 42 (29.8%) preeclamptic (PE). In another cohort we also evaluated MHbR activity in the following groups: n  = 18 PE, n  = 41 NT-pregnant, n  = 32 fetuses of NT-pregnant women and n  = 11 fetuses of PE women. MHbR activity (mmol/gHb/min) was determined in erythrocytes of pregnant women and umbilical cord by a spectrophotometric method. For statistical analysis Student t -test and binary regression logistic were used. P Results The MHbR activity did not significantly differed between PE women and NT-pregnant women (18.1 ± 1.2 versus 17.6 ± 0.6). When adjusted MHbR activity for age, we observed that did not influenced the MHbR activity, yet the effect of age was significantly modulated by MHbR activity in PE women in relation to NT-pregnant women (OR = 1.1, 95%CI 1.00–1.19, P  = 0.040). From another cohort, MHbR activity was higher in PE women in relation to NT-pregnant women (23.4  ±  10.4 versus 16.9  ±  8.9). The MHbR activity was higher in fetuses of PE women comparing with fetuses of NT-pregnant (14.3  ±  5.5 versus 12.5  ±  7.7). In relation to mothers, MHbR of fetuses of PE women was lower than their mothers (14.3  ±  5.9 versus 23.4  ±  10.4). Conclusions MHbR (CYB5R3) enzyme appears to respond directly to existing levels of oxidative stress in pregnancy and this is exacerbated in preeclampsia, even in fetuses. This can have implications in the use of NO therapy in preterm infants, born in these situations.