Differences in perinatal NaCl exposure alters blood pressure levels of adult rats

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Abstract
To determine the effect of differences in NaCl intake early in development on adult blood pressure levels, adult Sprague-Dawley female rats were maintained on diets containing either 0.12, 1.0, or 3.0% dietary NaCl throughout pregnancy and lactation. The offspring were continued on these same diets to 30 days postpartum. Thereafter, all offspring were maintained on the same stock diet containing 1% NaCl. Beginning at 60 days, systolic blood pressure and heart rate were measured weekly for the next 6 wk by tail-cuff plethysmography in lightly etherized rats. Mean arterial pressure (MAP) and heart responses to the subcutaneous sequential administration of 100 micrograms/kg angiotensin II and 15 micrograms/kg isoproterenol were then obtained from the catheterized femoral or carotid artery in awake unrestrained rats. Rats raised on 3% NaCl diet had significantly higher base-line MAPS (127.1 mmHg) than rats raised on the 1% (117.4 mmHg) or 0.12% (115.8 mmHg) salt diets. The highest salt group was also significantly more responsive to the pressor effects of angiotensin II (+46.4 mmHg) and the depressor effects of isoproterenol (-41.4 mmHg) than the mid- (+35.6 and -32.2 mmHg) and low- (+26.9 and -32.5 mmHg) salt groups. Thus there is a sensitive period early in ontogenesis of the normotensive Sprague-Dawley rat during which blood pressure and blood pressure responsiveness to angiotensin II and isoproterenol may be influenced permanently by dietary NaCl.