51 Differences in sodium intake determine the blood pressure phenotype in pregnant rats

Abstract

Background In pregnancy, plasma volume expansion by high aldosterone levels is crucial to prevent placental ischaemia, a condition linked to maternal arterial hypertension. Objective We hypothesise that an adapted salt intake will further lead to a favourable maternal blood pressure response. Methods Sprague–Dawley rats were followed by blood pressure telemetry and metabolic measurements before mating and throughout pregnancy in four experimental groups receiving either normal (NS; 0.4%), high (HS; 8%), low (LS; 0.01%), or high (8%) for the first 14 d of pregnancy followed by a switch to low Na + diet (0.01%) until day 20 (HS/LS). On day 20 the animals were sacrificed. Food, water and Na + balance was recorded. Results In pregnancy, Na + intake ( p = 0.02) and retention ( p = 0.004) increased already in NS conditions. The ratio of Na + intake vs. excretion was high in pregnant rats on NS ( p = 0.015) and LS ( p = 0.008 vs. non-pregnant) diet and low ( p p = 0.004–0.044 vs. non-pregnant) as compared to NS diet ( p Conclusions Pregnancy determines the response to dietary changes in salt intake aiming to preserve salt thus overcoming periods of low salt availability as shown in our HS/LS model. Increased salt intake reduces maternal blood pressure in pregnancy. Though the exact dose and temporal relationship needs to be elucidated, these results highlight the important role of environmental factors, such as salt, for a successful pregnancy.