The effect of angiotensin AT1 receptor blockade in the brain on the maintenance of blood pressure during haemorrhage in sheep

Acta Physiologica Scandinavica
M L MathaiM J McKinley

Abstract

The effect of systemic or intracerebroventricular (ICV) infusion of the angiotensin AT1 receptor antagonist losartan on blood pressure during hypotensive haemorrhage was investigated in five conscious sheep. Mean arterial pressure (MAP) was measured during haemorrhage (15 mL kg-1 body wt). Losartan (1 or 0.33 mg h-1) was given to sheep by ICV, intravenous or intracarotid administration, beginning 60 min before and continuing during the haemorrhage. During control infusion of ICV artificial cerebrospinal fluid, MAP was maintained until 13.16 +/- 0.84 mL kg-1 blood loss, when a rapid reduction of at least 15 mmHg in arterial pressure occurred (the decompensation phase). ICV infusion of losartan at 1 mg h-1 caused an early onset of the decompensation phase after only 9.8 +/- 0.8 mL kg-1 of blood loss compared with control. Intravenous infusion of losartan (1 mg h-1) also caused an early onset (P < 0.05) of the decompensation phase at 10.2 +/- 1.0 mL kg-1 blood loss. This dose of losartan inhibited the pressor response to ICV angiotensin II, but not to intravenously administered angiotensin II, indicating that only central AT1 receptors were blocked. Bilateral carotid arterial administration of losartan at 0.33 mg h-1 caused an ear...Continue Reading

Citations

Aug 24, 2002·Pediatric Research·Sithembiso C VelaphiCharles R Rosenfeld
Apr 12, 2007·Pediatric Research·Sithembiso C VelaphiCharles R Rosenfeld
Jun 16, 2004·American Journal of Transplantation : Official Journal of the American Society of Transplantation and the American Society of Transplant Surgeons·Mohamad H YamaniRandall C Starling
Aug 9, 2001·The Japanese Journal of Physiology·M J McKinleyR S Weisinger
Apr 29, 2006·Laterality·Richard GriffinHiram Brownell
Sep 15, 2007·American Journal of Physiology. Regulatory, Integrative and Comparative Physiology·Peter S P TanRoger A L Dampney
Nov 24, 2019·European Journal of Pharmacology·Maycon I O MilanezRuy R Campos

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