Effects of atrial natriuretic peptide on inter-organ crosstalk among the kidney, lung, and heart in a rat model of renal ischemia-reperfusion injury

BACKGROUND Renal ischemia-reperfusion injury (IRI) is a common cause of acute kidney injury and a frequent occurrence in critically ill patients. Renal IRI releases proinflammatory cytokines within the kidney that induce crosstalk between the kidney and other organ systems. Atrial natriuretic peptide (ANP) has anti-inflammatory as well as natriuretic effects and serves important functions as a regulator of blood pressure, fluid homeostasis, and inflammation. The objective of the present study was to elucidate whether ANP post-treatment attenuates kidney-lung-heart crosstalk in a rat model of renal IRI. METHODS In experiment I, a rat model of unilateral renal IRI with mechanical ventilation was prepared by clamping the left renal pedicle for 30 min. Five minutes after clamping, saline or ANP (0.2 μg/kg/min) was infused. The hemodynamics, arterial blood gases, and plasma concentrations of lactate and potassium were measured at baseline and at 1, 2, and 3 h after declamping. The mRNA expression and localization of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 in the kidney, lung, and heart were examined. In experiment II, a rat model of bilateral renal IRI without mechanical ventilation was prepared by clamping bilateral renal pedicles for 30 min. Thirty minutes after clamping, lactated Ringer's (LR) solution or ANP (0.2 μg/kg/min) was infused. Plasma concentrations of TNF-α, IL-6, and IL-1β were determined at baseline and at 3 h after declamping. RESULTS In unilateral IRI rats with mechanical ventilation, ANP inhibited the following changes induced by IRI: metabolic acidosis; pulmonary edema; increases in lactate, creatinine, and potassium; and increases in the mRNA expression of TNF-α, IL-1β, and IL-6 in the kidney and lung and IL-1β and IL-6 in the heart. It also attenuated the histological localization of TNF-α, IL-6, and nuclear factor (NF)-κB in the kidney and lung. In bilateral IRI rats without mechanical ventilation, ANP attenuated the IRI-induced increases of the plasma concentrations of potassium, IL-1β, and IL-6. CONCLUSIONS Renal IRI induced injury in remote organs including the lung and the contralateral kidney. ANP post-treatment ameliorated injuries in these organs by direct tissue protective effect and anti-inflammatory effects, which potentially inhibited inter-organ crosstalk.