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Arterial baroreceptor reflex function in borderline hypertensive rats.
1Department of Internal Medicine, University of Iowa College of Medicine, Iowa City 52242.
Hypertension (Dallas, Tex. : 1979)
|January 1, 1992
Summary
High salt intake causes hypertension in borderline hypertensive rats, but their arterial baroreceptor reflex function remains intact. This suggests salt-induced hypertension does not impair baroreflex control in this model.
Area of Science:
- Cardiovascular Physiology
- Renal Physiology
- Hypertension Research
Background:
- Borderline hypertensive rats (BHR) develop hypertension with high dietary salt (8% NaCl).
- Spontaneously hypertensive rats (SHR) exhibit impaired arterial baroreceptor reflex function.
- Investigating baroreflex function in salt-induced hypertension in BHR is crucial.
Purpose of the Study:
- To examine arterial baroreceptor reflex function in BHR made hypertensive by high NaCl intake.
- To compare baroreflex control of heart rate and renal sympathetic nerve activity (RSNA) between salt-loaded and control BHR.
Main Methods:
- BHR were fed 1% or 8% NaCl from 4 to 16 weeks of age.
- Arterial pressure, heart rate, and RSNA were recorded in conscious rats.
- Baroreceptor reflex sensitivity was assessed using phenylephrine and nitroglycerine challenges.
Main Results:
- Rats fed 8% NaCl exhibited significantly higher arterial pressure (141 mmHg) than controls (120 mmHg).
- Arterial baroreceptor reflex control of heart rate showed no significant difference in range or gain between groups.
- Arterial baroreceptor reflex control of RSNA also showed no significant difference in range or gain between groups.
Conclusions:
- Dietary NaCl loading induces hypertension in BHR without impairing arterial baroreceptor reflex function.
- This contrasts with the impaired baroreflex seen in SHR, suggesting different mechanisms in salt-induced hypertension.
- BHR model with salt-induced hypertension may be useful for studying factors other than baroreflex impairment.