Age differences in blood pressure and norepinephrine concentration in normotensive rats after higher doses of estrogen.

1. Normotensive rats (3 months old) showed 6-9% increases in blood pressure (B.P.) after high doses of estrogen, with increases in hypothalamic and adrenal norepinephrine (NE). 2. Older normotensive rats (6 months old) showed 4-11% increases in B.P. after high doses of estrogen with a decrease in brainstem NE.