Objective: To investigate the involvement of intestinal angiotensin II type 2 receptors in the outcome of acute severe hypovolemia as well as systemic and regional mesenteric hemodynamics and intestinal mucosal functions in anesthetized pigs. Design and setting: Prospective, interventional animal study in a university research laboratory. Subjects: 53 landrace pigs, 28-35 kg. Interventions: 30+30% or 20+20% hemorrhage of estimated total blood volume followed by retransfusion performed in untreated controls, in animals treated with the angiotensin II type 1 receptor blocker candesartan or with a combination of candesartan and the angiotensin II type 2 receptor blocker PD123319. Measurements and results: Following 30+30% hemorrhage the candesartan-treated animals attained a significantly higher survival rate than controls and animals treated with PD123319 in combination with candesartan. Less pronounced hemorrhage (20+20%) resulted in no mortality and functional variables were assessed. A significantly higher output of jejunal intraluminal nitric oxide occurred during hypovolemia in the candesartan treated group than in controls and animals that received PD123319 in combination with candesartan. Jejunal transmucosal potential difference was significantly better preserved after retransfusion in candesartan-treated animals than in controls. Expression of angiotensin II type 2 receptors in intestinal tissue was significantly higher in animals surviving the 30+30% hemorrhage than in nonsurvivors. Conclusions: Lethal circulatory failure is possibly influenced by use of angiotensin receptor ligands, and activation of intestinal angiotensin II type 2 receptors may play a significant role in improving the outcome of severe hypovolemia.
- Angiotensin II receptors
- Renin-angiotensin system