Pregnancy is associated with increases in maternal cardiac output and plasma volume and a reduction in peripheral vascular resistance. Cardiac output and plasma volume are substantially reduced in pregnant rats fed a low-protein diet, but it is not known whether vascular function is also compromised. We have investigated vascular function in virgin and pregnant Wistar rats subjected to dietary protein restriction [9% (w/v) casein, compared with 18% (w/v) casein for controls]. The diets were fed to the groups for 18 days; in the pregnant rats, the diets were given from day 1 of pregnancy. Branches of the mesenteric arteries were studied on day 18 of the dietary period using myography. Significant reductions in sensitivity to acetylcholine occurred in vessels from virgin ( P = 0.04) and pregnant ( P = 0.01) rats that had consumed the 9% casein diet. In arteries from the virgin rats on the restricted diet there was also a significant reduction in sensitivity ( P = 0.0003) and maximum relaxation ( P = 0.009) to the NO donor spermine NONOate. Mean placental and fetal weights were significantly lower in the rats fed on 9% casein ( P <0.0001 and P = 0.005 respectively). Thus low-protein diets impair vasodilator responses in female rats. These effects may contribute to the poor cardiovascular adaptation to pregnancy and lower fetal weights associated with restricted protein intake.
1. The objectives of the study were: (i) to investigate the serum concentrations of vascular endothelial growth factor (VEGF) in pregnant and non-pregnant women; and (ii) to study the relationship between the levels of maternal serum VEGF and the serum concentrations of human chorionic gonadotrophin (hCG) and progesterone during the first trimester. 2. Total immunoreactive VEGF was measured by competitive RIA using recombinant human VEGF 165 and a polyclonal antiserum. Serum VEGF was measured in 60 non-pregnant women of child-bearing age. These data were compared with serum VEGF measured in 363 women between 41 and 91 days of gestation. 3. The median serum VEGF concentration was 1.10 μg/l (interquartile range 0.91–1.30) in the nonpregnant women and 2.13 μg/l (interquartile range 1.62–2.77) in the pregnant women. Serum levels of VEGF were significantly higher among the pregnant cohort ( P < 0.0001). Serum VEGF concentration was positively correlated with gestational age, increasing until ten completed weeks of pregnancy. Serum VEGF was negatively correlated with maternal height and weight, and positively correlated with serum hCG and serum progesterone ( P ≤ 0.0001 in all cases). Serum VEGF was lower in the pregnant women who smoked ( P = 0.06). 4. Our data show a positive and highly significant correlation between maternal serum levels of VEGF and hormones reflecting placental function (hCG, progesterone). We speculate that VEGF production is increased by progesterone and hCG, and that VEGF has a positive influence on trophoblast development. VEGF may also be involved in the initiation of the maternal cardiovascular adaptation to pregnancy.