Stress-sensitive arterial hypertension and tolerance to the salt loading in the ISIAH rats

Abstract

The aim of the study is to investigate the ability of ISIAH rats with stress-sensitive arterial hypertension
to cope with the salt loading. Hypertensive ISIAH and normotensive WAG rats were kept in metabolic
cages for 7 days on three drinking regimes: group 1 – no salt loading (tap water), group 2 – saline
solution (0.87% NaCl), and group 3 – 1,5% NaCl solution. After 7 days, no significant changes in the
blood pressure in either WAG or ISIAH rats was observed. No differences between hypertensive and
normotensive rats were found in the ability to excrete NaCl with urine. Glomerular filtration rates in
ISIAH rats receiving both isotonic (saline) and hypertonic salt solutions were significantly higher than
in the corresponding groups of WAG rats. In ISIAH, but not in WAG rats, receiving a hypertonic salt
solution was accompanied by an increase in the concentrations of norepinephrine and epinephrine
in urine. No significant changes in the function of renin-aldosterone system were observed. These and
previously obtained results lead to the conclusion that not renal mechanisms but rather sympathetic
nervous activity underlies the early development of arterial hypertension in stress-sensitive ISIAH
rats, which are well tolerated to the salt loadings at this period of ascending pathology.