RISE OF BLOOD-PRESSURE IN CALCIUM-DEPRIVED PREGNANT RATS

Ca intake may be inversely related to blood pressure (BP) in animals and pregnant women. To test this hypothesis, 34 female, 142-day-old Wistar rats were studied prospectively. They were randomly assigned to either a Ca-free diet (16 rats) or a normal diet (18 rats). Weekly measurements of tail systolic BP showed a statistically significant increase in BP in the Ca-free group after 6 wk of treatment. After 9 wk on this diet, the animals were mated. Five in the control group and 6 in the Ca-free group became pregnant. Thereafter, both subgroups (pregnant and nonpregnant Ca-free diet) continued with significantly higher BP until they were put to death. Blood samples taken at the end of the study showed significantly lower values of Ca/Mg ratio, but higher Pi in the group consuming a Ca-free diet. Blood pressure during the last 3 wk was significantly inversely correlated with the blood Ca/Mg ratio and directly correlated with Mg and Pi values. Thus a low-Ca diet is associated with high BP in pregnant and nonpregnant female rats.