Corin (an atrial natriuretic peptide converting enzyme) represents a potential biomarker for gestational hypertensive disorders; yet, its role in blood pressure regulation throughout pregnancy remains unclear. We investigated the time-course of change in blood corin content in relation to blood pressure and sympathetic nerve activity throughout pregnancy. Forty-four women (29±0.9 yrs) participated. Following-term, 23 had 'low-risk' (no personal history of gestational hypertensive disorders) normal pregnancies, 13 had 'high-risk' (personal history of gestational hypertensive disorders) normal pregnancies, and eight developed gestational hypertension. Blood pressure, heart rate, muscle sympathetic nerve activity, and serum corin were measured prior-to pregnancy, during early-(4-8 wks) and late-pregnancy (32-36 wks), and post-partum (6-10 wks). Overall, compared to pre-pregnancy, corin remained unchanged during early-pregnancy, increased markedly during late-pregnancy (P<0.001), and returned to pre-pregnancy levels post-partum. In women who developed gestational hypertension, the change in corin from early-to late-pregnancy was greater than those with 'low-risk' normal pregnancies (Δ971±134 vs. Δ486±79 pg/mL; P<0.05). Throughout pregnancy, blood pressure and muscle sympathetic nerve activity were augmented in women with gestational hypertension (all P<0.05). Finally, changes in corin from early-to late-pregnancy were related to all indices of blood pressure (R=0.454-0.551; all P<0.01) in late-pregnancy, whereas burst frequency, burst incidence, and total muscle sympathetic nerve activity (R=0.576-0.614; all P<0.001) in early-pregnancy were related to changes in corin from early-to late-pregnancy. Corin plays a unique role in blood pressure regulation throughout

Key pointsr Asian women have a lower prevalence of hypertensive disorders of pregnancy than Caucasian women.r This is the first longitudinal study to investigate neural and humoral responses during pregnancy in Asians and Caucasians.r The key finding was that Asians had attenuated sympathetic activation but enhanced renal-adrenal responsiveness during pregnancy compared to Caucasians.r These results may provide insights into the pathophysiological mechanisms for racial differences in the prevalence of hypertensive disorders during pregnancy.Abstract Asians have a lower prevalence of hypertensive disorders of pregnancy than Caucasians. Since sympathetic overactivity and dysregulation of the renal-adrenal system (e.g. low aldosterone levels) have been found in preeclamptic women, we hypothesized that Asians have lower muscle sympathetic nerve activity (MSNA) and greater aldosterone concentrations during normal pregnancy than Caucasians. In a prospective study, blood pressure (BP), heart rate (HR), and MSNA were measured during supine and upright tilt (30 deg and 60 deg for 5 min each) in 9 Asians (32 ± 1 years (mean ± SEM)) and 12 Caucasians (29 ± 1 years) during pre-, early (ࣘ8 weeks of gestation) and late (32-36 weeks) pregnancy, and post-partum (6-10 weeks after delivery). Supine MSNA increased with pregnancy in both groups (P < 0.001); it was significantly lower in Asians than Caucasians (14 ± 3 vs. 23 ± 3 bursts min −1 and 16 ± 5 vs. 30 ± 3 bursts min −1 in early and late pregnancy, respectively; P = 0.023). BP decreased during early pregnancy (P < 0.001), but was restored during late pregnancy. HR increased during pregnancy (P < 0.001) with no racial difference (P = 0.758). MSNA increased during tilting and it was markedly lower in Asians than Caucasians in late pregnancy (31 ± 6 vs. 49 ± 3 bursts min −1 at 60 deg tilt; P = 0.003). Upright BP was lower in Asians, even in pre-pregnancy (P = 0.006), and this racial difference persisted during pregnancy. Direct renin and aldosterone increased during pregnancy (both P < 0.001); these hormones were greater in Asians (P = 0.086 and P = 0.014). Thus, Asians have less sympathetic activation but more upregulated renal-adrenal responses than Caucasians during pregnancy. These results may explain, at least in part, why Asian women are at low risk of hypertensive disorders in pregnancy.