Blood pressure development and serum calcium in suckling spontaneously hypertensive rat pups: effects of maternal dietary calcium.

Since perinatal factors and dietary calcium intake have been implicated in the early pathogenesis of hypertension in the spontaneously hypertensive rat (SHR), the effect of maternal dietary calcium intake on blood pressure development in the 3-4-week-old suckling SHR was assessed. Twenty-four 6-week-old female SHR were randomized to either a calcium- (0.1%) and sodium- (0.25%) restricted or calcium- (2.0%) and sodium- (1.0%) supplemented diet. After 19 weeks on the diet they were bred. Immediately following birth, half of the pups were cross-fostered to a dam on the alternative diet and half were fostered to a dam on the same diet as that to which they were exposed in utero. Between the 25th and 28th post-natal day each pup had an intra-arterial catheter placed in a femoral artery. Mean arterial pressure (MAP), serum ionized calcium and total calcium were measured. Pups fostered to dams on restricted-Ca2+ diets had higher MAP (P less than 0.01) and lower serum ionized (P less than 0.01) and total (P less than 0.01) calcium levels. There was a significant inverse correlation between serum ionized Ca2+ and MAP in the pups (r = -0.61, P greater than 0.001). We conclude that maternal dietary calcium intake may be an important perinatal factor in the blood pressure development of the suckling SHR.