Abstract
Moderate hypothermic circulatory arrest (moderate HCA) with selective cerebral perfusion has been developed for cerebral protection during thoracic aortic surgery. However, visceral organs, particularly the kidneys, suffer great tissue damage under moderate HCA, and acute renal failure after HCA is an independent risk factor for early and late mortality. The present study investigates whether atrial natriuretic peptide (ANP) can prevent a reduction in renal perfusion and protect renal function after moderate HCA. Twelve pigs (weight 36.7 ± 1.7kg), cooled to 30°C by a cardiopulmonary bypass, were randomly assigned into an ANP group (n = 6) treated with recombinant ANP (0.05μg/kg/min) and a control group (n = 6); moderate HCA was subsequently induced for 60 minutes. Systemic arterial mean pressure and renal artery flow did not significantly differ between the two groups during the study. The renal medullary blood flow was significantly increased in the ANP group after HCA (109.3 ± 35.7% vs. 207.5 ± 113.2%; p = 0.03). Myeloperoxidase activity was significantly reduced in the medulla of the ANP group (0.057 ± 0.035 vs. 0.026 ± 0.019U/mg; p = 0.03). Renal medullary ischemia after HCA was ameliorated by ANP by increasing medullary blood flow and by reducing sodium reabsorption in the medulla. Additionally, ANP reduced the inflammatory properties produced after ischemia in the renal tissues.
