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