DIETARY SALT INTAKE MODULATES ANGIOTENSIN-II TYPE-1 RECEPTOR GENE-EXPRESSION

This study aimed to characterize the influence of dietary salt intake on the gene expression of angiotensin II type 1 (AT(1)) receptor subty pes in different organs. Male Sprague-Dawley rats were fed low salt (0 .2 mg/g), normal salt (6 mg/g), or high salt (40 mg/g) diets for 5, 10 , and 20 days. mRNA levels for the two AT(1) receptor subtypes were de termined in adrenal gland, kidney, liver, and lung. In all of the orga ns examined, with the exception of the adrenal glands, low salt diet l ed to a transient decrease in the abundance of AT(1A) receptor mRNA bu t not of AT(1B) mRNA, which reached their nadirs between days 5 and 10 of feeding. In the adrenal gland, in which the AT(1B) receptor is pre dominant, low salt diet led to a transient increase in the expression of this receptor gene, with a maximum around day 10 of feeding. High s alt diet exerted no significant influence on AT(1) receptor gene expre ssion in these organs. These findings indicate that the rate of salt i ntake, in particular, a reduction of salt intake, significantly influe nces AT, receptor gene expression in an organ-, time-, and subtype-dep endent fashion. It appears that AT(1) receptor subtypes are differenti ally influenced by low salt intake, in that AT(1B) receptor gene expre ssion increases and AT(1A) receptor gene expression decreases in this situation. This differential response of AT(1) receptor gene expressio n may be relevant for the organism to be able to adapt to a reduction in oral salt intake.