Hypertension in Dahl salt-sensitive rats: biochemical and immunohistochemical studies.
1. The renin-angiotensin and kinin-kallikrein systems of Dahl salt-sensitive and salt-resistant rats fed diets with different salt contents were analysed using biochemical and immunocytochemical techniques. 2. Blood pressure increased by 45% in salt-sensitive rats only, after 4 weeks on a high-salt diet. The plasma renin activity and plasma angiotensin II concentration remained at the same levels in salt-sensitive rats on the high-salt diet as on the normal salt diet, whereas the plasma renin activity and plasma angiotensin II concentration of salt-resistant rats fed the high-salt diet were lower. The plasma renin activity and the plasma angiotensin II concentration were elevated in both salt-resistant and salt-sensitive rats fed the salt-deficient diet but were much more elevated in salt-resistant than in salt-sensitive rats. 3. The kidney immunocytochemical data paralleled the data on plasma parameters. Salt-sensitive rats had fewer renin positive juxtaglomerular apparatuses than salt-resistant rats on the normal diet, and the increase on the sodium-deficient diet was also smaller in salt-sensitive rats. Salt-sensitive rats fed the high-salt diet and the standard diet had almost no angiotensin II immunoreactivity compared with the salt-resistant rats on the same diets. 4. The total renal kallikrein content of salt-sensitive rats was lower than that of salt-resistant rats on all three diets, as was the amount of kallikrein excreted in the urine on the standard and the high-salt diets. The differences resulted from a reduction in active kallikrein. The increase in kallikrein in salt-sensitive and salt-resistant rats on the salt-deficient diet was not significantly different. 5. There were similar changes in immunopositive kallikrein in the kidneys of salt-sensitive and salt-resistant rats with diet, with a large increase in kallikrein biosynthesis on the low-salt diet. The plasma concentration of high-molecular-mass kininogen was not significantly different in salt-sensitive and salt-resistant rats, but there was a significant increase in T-kininogen in salt-sensitive rats fed the high-salt diet. 6. In conclusion, the absence of decreases in the plasma renin activity and the plasma angiotensin II concentration in salt-sensitive rats fed the high-salt diet might partially explain the increase in blood pressure.
Bouhnik
J
J
INSERM U36 and U367, Paris, France.
Richoux
J P
JP
Huang
H
H
Savoie
F
F
Baussant
T
T
Alhenc-Gelas
F
F
Corvol
P
P
D000804:Angiotensin II / Q000032:analysis / Q000097:blood; D000818:Animals; D006973:Hypertension / Q000097:blood* / Q000139:chemically induced; D007150:Immunohistochemistry; D016234:Kallikrein-Kinin System / Q000502:physiology*; D007610:Kallikreins / Q000032:analysis; D007668:Kidney / Q000737:chemistry / Q000473:pathology / Q000503:physiopathology*; D008297:Male; D009929:Organ Size; D051381:Rats; D011919:Rats, Inbred Strains / Q000502:physiology*; D012083:Renin / Q000032:analysis / Q000097:blood; D012084:Renin-Angiotensin System / Q000502:physiology*; D012982:Sodium, Dietary / Q000008:administration & dosage* / Q000009:adverse effects; D013997:Time Factors
D012982:Sodium, Dietary; D000804:Angiotensin II; D007610:Kallikreins; D012083:Renin