NEONATAL AND MATERNAL PLATELET CYTOSOLIC CALCIUM IN NORMOTENSIVE AND HYPERTENSIVE PREGNANCIES

A prospective study investigated platelet cytosolic calcium in non-pregnant volunteers (n=30) and samples from the umbilical veins of babies from both normotensive (n=18) and hypertensive (n=15) primigravidae, and their mothers. There was no significant difference between the neonatal umbilical venous platelet cytosolic calcium concentration (p[Ca2+]i) in babies born to normotensive primigravidae or to those whose pregnancies were complicated by gestational hypertension (88.9 (SE) 2.5) in normotensive primigravidae, 80.6 (2.8) in pregnancy induced hypertension without proteinuria, and 89.3 (3.2) nmol/l in pre-eclampsia. There was also no significant difference in the p[Ca2+]i from the umbilical veins of the pregnancies studied and those of non-pregnant female volunteers in the follicular phase of their menstrual cycle. This was despite a gradual and significant rise in p[Ca2+]i with increasing severity of disease in the mothers of the babies studied (119.9 (4.1) in normotensive primagravidae, 130.8 (7.3) in pregnancy induced hypertension without proteinuria, and 148.2 (4.5) nmol/l in pre-eclampsia). The mean maternal p[Ca2+]i in the three samples returned to concentrations comparable with those in non-pregnant subjects by 12 weeks after birth. These data demonstrate no significant difference between the mean p[Ca2+]i in non-pregnant women and those obtained from the umbilical venous blood of normotensive or hypertensive primigravidae. They suggest that the functional hypoactivity of neonatal platelets is probably not secondary to a decrease in basal p[Ca2+]i. They also suggest that the progressively raised p[Ca2+]i in normal and hypertensive pregnancies might be due to a pregnancy specific factor that does not cross the placenta.