title: Role of blood volume expansion in Dahl rat model of hypertension.
abstract: Continuous measurement and servo control (SC) of total body weight of unrestrained rats were used to investigate the role of volume expansion in the development of hypertension in Dahl salt-resistant (SR) and Dahl salt-sensitive (SS) rats. A change in sodium intake from 1 to 20 meq/day was associated with an increase in total body weight of 7.2% in both SS and SR rats over 96 h. Plasma sodium (pNa) increased from 145.0 to 147.4 meq/l in both SS (n = 10) and SR (n = 10) rats. Only in the SS rats was the volume expansion associated with an increase in arterial pressure of 27 +/- 3 mmHg. Prevention of the volume expansion by SC blocked the rise in arterial pressure in the SS rats (n = 10) but increased pNa from 143.5 to 152.4 meq/l. Hematocrit fell from 36.6 to 27.5% in both non-SC groups but decreased less in SC groups (35.7 to 32.0%). Plasma volume expansion from 17.6 +/- 0.6 to 25.2 +/- 0.8 ml in non-SC rats was greatly blunted by SC. In non-SC rats, SS (n = 10) and SR (n = 9) rats an increase in salt intake was associated with a rise in cardiac output from 413 +/- 6 to 507 +/- 12 ml.min-1.kg-1 in both groups. These results indicate that fluid retention is required to trigger the rise of pressure in Dahl SS rats.
authors.affiliation: Department of Physiology, Medical College of Wisconsin, Milwaukee 53226.
authors.forename: A S
authors.initials: AS
authors.lastname: Greene
authors.forename: Z Y
authors.initials: ZY
authors.lastname: Yu
authors.forename: R J
authors.initials: RJ
authors.lastname: Roman
authors.forename: A W
authors.initials: AW
authors.lastname: Cowley
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001810:Blood Volume / Q000502:physiology*; D002302:Cardiac Output; D004032:Diet; D004351:Drug Resistance; D006973:Hypertension / Q000209:etiology*; D051381:Rats; D011919:Rats, Inbred Strains; D011922:Rats, Mutant Strains; D012964:Sodium / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology; D012965:Sodium Chloride / Q000494:pharmacology
chemical_list: D012965:Sodium Chloride; D012964:Sodium