Alterations in the Renin-Angiotensin System in Experimental Septic Shock

OBJECTIVES:. To analyze dynamic changes in the renin-angiotensin system (RAS) during septic shock, focusing on angiotensin-converting enzyme (ACE) activity and the balance between angiotensin peptides, using a mass spectrometry method. DESIGN:. Experimental septic shock model induced by peritonitis in swine. SETTING:. Experimental Laboratory, Department of Intensive Care, Erasme Hospital, Université Libre de Bruxelles. SUBJECTS:. Forty time points from eight mechanically ventilated pigs. INTERVENTIONS:. Septic shock was induced using intraperitoneal instillation of autologous feces, followed by standardized fluid resuscitation, norepinephrine infusion, antibiotic administration, and peritoneal lavage. MEASUREMENTS AND MAIN RESULTS:. The induction of sepsis resulted in a significant increase in plasma renin activity and levels of angiotensin I and II, with a significant decrease in ACE activity observed from 4 hours post-resuscitation and a notable rise in the angiotensin I/angiotensin II ratio at 12 hours. Additionally, a shift toward the angiotensin-(1–7) axis was observed, evidenced by an increased angiotensin-(1–7)/angiotensin II ratio. CONCLUSIONS:. The study highlighted dynamic shifts in the RAS during septic shock, characterized by reduced circulating ACE activity, elevated angiotensin I/II ratio, and a shift toward the angiotensin-(1–7) axis. These findings suggest an adaptive response within the RAS, potentially offering new insights into sepsis management and therapeutic targets.