Potentiation of the pressor effect of angiotensin II by intraventricular infusion of hypertonic saline.
The effect of selective NaCl loading to the brain on the blood pressure regulation was examined in male Wistar rats. Hypertonic NaCl (0.8M, 1 microL/h) was infused for 7 days into the lateral ventricle (ICV) along with intravenous (IV) infusion of angiotensin II (AII) at a dose of 5.4 pmol/kg per minute. Although neither ICV hypertonic NaCl or IV AII infusion alone had any substantial pressor effect, concomitant administration of these resulted in a consistent and significant increase in the blood pressure on day 7 over the baseline value, amounting to 29 +/- 5 mm Hg (n = 9; P less than 0.001). Inasmuch as the increase in the BP was totally prevented by intraperitoneal injection of guanethidine (40 mg/day), hyperactivity of the sympathetic nervous system appears, at least in part, responsible for the BP elevation caused by the combination of ICV hypertonic NaCl and IV subpressor AII infusion.
Department of Medicine and Geriatrics, Osaka University Medical School, Japan.
H
H
Mikami
K
K
Katahira
T
T
Ogihara
K
K
Kohara
A
A
Otsuka
Y
Y
Kumahara
D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D002552:Cerebral Ventricles / Q000502:physiology*; D004357:Drug Synergism; D007276:Injections, Intraventricular; D012462:Saline Solution, Hypertonic / Q000494:pharmacology*; D012965:Sodium Chloride / Q000494:pharmacology*
D012462:Saline Solution, Hypertonic; D000804:Angiotensin II; D012965:Sodium Chloride