Cardiovascular reflexes in conscious sodium-depleted rats.
Reflex arterial pressure regulation was studied in control and sodium-depleted rats fed a diet containing 0.1 mEq Na+ for 6 days associated with furosemide (5 mg/kg, ip, on the 1st and 5th day). The hypertensive response produced in conscious rats by bilateral common carotid occlusion (5 to 60 s) was significantly smaller in the sodium-depleted rats (MAP = 113 +/- 3 mmHg) than in the controls (MAP = 121 +/- 2 mmHg) in terms of absolute as well as relative values. Sixty min after recovery from ether anesthesia, the rats submitted to sino-aortic denervation showed a similar relative increase in MAP (30%), whereas the hypertensive level attained by the sodium-depleted rats was only mild (MAP = 126 +/- 5 mmHg). Sodium-depleted rats required 3.5 and 2.4 times larger dose of norepinephrine and angiotensin II, respectively, than the control rats to produce an increase in MAP of 20-25 mmHg. Changes in vascular reactivity associated with impaired cardiac function might be important factors to explain the decreased pressor responses produced by carotid occlusion and by sino-aortic denervation in sodium-depleted rats.
D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D002339:Carotid Arteries / Q000601:surgery; D003714:Denervation; D004039:Diet, Sodium-Restricted; D005665:Furosemide / Q000494:pharmacology*; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012084:Renin-Angiotensin System / Q000187:drug effects*; D012965:Sodium Chloride / Q000494:pharmacology*
D000804:Angiotensin II; D012965:Sodium Chloride; D005665:Furosemide; D009638:Norepinephrine