Effects of dietary sodium alterations during preweanling
development on renin and angiotensinogen gene expression in wky and
shr.
Kirby, Robert F., William V. Page, Alan Kim Johnson, and Jean E.
Robillard.
Departments of Psychology, Pharmacology, Pediatrics, and the
Cardiovascular Center, The University of Iowa
APStracts 3:0164R, 1996.
The present study examined the influence of altered dietary sodium on
angiotensinogen and renin gene expression in young normotensive
Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR). The
technique of artificial rearing was used to increase or decrease
dietary sodium intake during the preweanling period. In normally
-reared control animals, there was an age dependent decrease in renal
renin and liver angiotensinogen mRNA between 6 and 30 postnatal days
of age. In contrast, there was a markedly different developmental
pattern for angiotensinogen and renin gene expression in the central
nervous system, with angiotensinogen mRNA increasing between 6 and 30
days of age and renin mRNA remaining stable. The only strain related
difference in gene expression was an increase in angiotensinogen mRNA
on postnatal days 18 and 30 in the hypertensive strain. The
manipulation of dietary sodium between postnatal days 6 and 18
significantly influenced renal renin gene expression, leading to
increased renin mRNA on postnatal days 12 and 18 with low dietary
sodium and decreased renin mRNA on day 18 with high sodium diet.
Liver angiotensinogen mRNA was decreased for animals on either low or
high sodium diets on postnatal days 12 and 18. Brain angiotensinogen
and renin mRNA were not affected by dietary sodium levels. There were
no strain related differences in the response to high and low dietary
sodium. The results of the present study demonstrate that (i)
components of the peripheral and central renin-angiotensin systems do
not have a common ontogenetic pattern of development, (ii) are
independently regulated in response to dietary sodium variations, and
(iii) young WKY and SHR share very similar ontogenetic patterns of
angiotensinogen and renin gene expression.
Received 10 September 1995; accepted in final form 23 April 1996.
APS Manuscript Number R560-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 8 May 96