DIETARY-SODIUM EFFECTS ON RENIN AND ANGIOTENSINOGEN GENE-EXPRESSION IN PREWEANLING WKY AND SHR

The influence of altered dietary sodium on angiotensinogen and renin g ene expression was examined in young normotensive Wistar-Kyoto (WKY) a nd spontaneously hypertensive rats (SHR). Artificial rearing was used to increase or decrease dietary sodium intake during the preweanling p eriod. In normally reared control animals, renal renin and liver angio tensinogen mRNA decreased between 6 and 30 postnatal days of age. In c ontrast, in the central nervous system, angiotensinogen mRNA increased between 6 and 30 days of age, and renin mRNA remained stable. Dietary sodium manipulation between postnatal days (PD) 6 and 18 significantl y influenced renal renin gene expression, with low-sodium diet increas ing renin mRNA on PD12 and PD18 and high-sodium diet decreasing renin mRNA on PD18. Liver angiotensinogen mRNA decreased for animals on eith er diet on PD12 and PD18. Brain angiotensinogen and renin mRNA were no t affected by dietary sodium levels. There were no strain-related diff erences in the response to high and low dietary sodium. These results demonstrate that I) the peripheral and central renin-angiotensin syste ms do not have a common ontogenetic pattern of development, 2) they ar e independently regulated in response to dietary sodium variations, an d 3) young WKY and SHR share very similar ontogenetic patterns of angi otensinogen and renin gene expression.