SEX DIFFERENCE IN BLOOD-PRESSURE OF SPONTANEOUSLY HYPERTENSIVE RATS INFLUENCED BY PERINATAL NACL EXPOSURE

Our prior study showed that the basal blood pressure level and pressor response to peripheral angiotensin II of adult Sprague-Dawley rats were enhanced by perinatal exposure to a high NaCl diet. The purpose of the present study was to assess further the relationship between NaCl-sensitivity of blood pressure and perinatal NaCl exposure. We tested the hypothesis that the basal blood pressure level and pressor responses to angiotensin II could be increased by perinatal exposure to high NaCl in NaCl-resistant spontaneously hypertensive rats (SHR-R). Adult female SHR-R were maintained on a diet containing either basal 1% or high 8% NaCl throughout pregnancy and lactation. The offspring were continued on these same diets to 30 days postpartum. Thereafter, all offspring were maintained on a diet containing 1% NaCl. After being adapted to restraint, systolic blood pressure was measured indirectly by the tail-cuff procedure when the rats were 30, 44, and 58 days of age. Subsequently, baseline mean arterial pressure (MAP) and pressor responses to intravenous administration of angiotensin II (20, 40, 80, and 120 ng/kg body weight) were obtained from the catheterized femoral artery in conscious unrestrained rats. The MAP levels of adult female SHR-R exposed perinatally to 8% NaCl were significantly greater than those of females exposed to 1% NaCl. This elevated blood pressure was accompanied by an elevation in plasma osmolality. Perinatal exposure to 8% NaCl did not raise the blood pressure and plasma osmolality levels of adult male SHR-R, but did enhance pressor responses to angiotensin II. On the basis of previous observations from other laboratories, we suggest that dietary NaCl manipulation during perinatal development modulates the sensitivity of central angiotensin II receptors and possibly central arginine vasopressin receptors and/or synthesis and release.