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In salt-sensitive rats, an 8% NaCl diet induced hypertension initially driven by increased blood volume and cardiac output at 4 weeks, shifting to increased total peripheral resistance by 8 weeks.
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Investigates cardiovascular effects of salt diets on Dahl rats, indicating distinct mechanisms for hypertension.
Cardiac output, blood volume, total peripheral resistance, and renal blood flow were measured in awake salt-sensitive and salt-resistant Dahl rats on normal rat chow (1% NaCl) and on high salt (8% NaCl) diets. Rats were studied after 4, 8, and 46 weeks on a 1% NaCl diet and after 4 and 8 weeks on an 8% NaCl diet. Salt-sensitive rats on 8% NaCl for 4 weeks developed systolic hypertension; by 8 weeks they developed greater systolic and also diastolic hypertension. Salt-resistant rats on 8% NaCl remained normotensive throughout the studies, although renal resistance decreased (p less than 0.05). At 4 weeks, hypertension in salt-sensitive rats on 8% NaCl was caused by increased blood volume and cardiac output (p less than 0.05), with normal total peripheral resistance. At 8 weeks, hypertension was due to increased total peripheral resistance (p less than 0.05); cardiac output was below normal despite persistent elevation of blood volume (p less than 0.05). Salt-sensitive rats on 1% NaCl for 46 weeks were hypertensive, with elevated total peripheral resistance (p less than 0.05); cardiac output decreased (p less than 0.05), whereas blood volume remained unchanged. Salt-resistant rats on 1% NaCl remained normotensive with no charges in hemodynamics. Salt-sensitive rats on 8% NaCl for 4 weeks had an increase in renal vascular resistance but no significant change in nonrenal resistance or total peripheral resistance. The increased total peripheral resistance in salt-sensitive rats on 8% NaCl for 8 weeks and on 1% NaCl for 46 weeks was a reflection of increases of both renal and nonrenal vascular resistance.(ABSTRACT TRUNCATED AT 250 WORDS)
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Simchon et al. (1991) studied Salt-induced hypertension. High salt diet vs. Normal rat chow (1% NaCl) was evaluated on Hemodynamic changes (blood volume, cardiac output, total peripheral resistance, and renal blood flow) (p=<0.05). In salt-sensitive rats, an 8% NaCl diet induced hypertension initially driven by increased blood volume and cardiac output at 4 weeks, shifting to increased total peripheral resistance by 8 weeks.
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