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Acute kidney injury is usually associated with distant organ dysfunction. The roles of inducible nitric oxide synthase (iNOS) and reactive oxygen species (ROS) in this phenomenon were investigated following 2 h unilateral renal ischemia and 24 h reperfusion. There were 3 groups of rats subjected to either unilateral ischemia/reperfusion (UIR group), unilateral nephrectomy (UNX group), or sham operation. Two further groups were given α-tocopherol and aminoguanidine with UIR (treated- UIR group) and UNX (treated-UNX group). Plasma nitrite/nitrate and malondialdehyde were elevated only in the UIR group. Creatinine clearance and blood flow increased in non-ischemic kidney of the UIR, but not to the same extent as remnant kidney of the UNX group, while they had equal compensatory rises in absolute [Na.sup.+] and [K.sup.+] excretion and urine flow. Non- ischemic kidney of the treated-UIR group, but not remnant kidney of the treated-UNX group, showed more elevation in blood flow, whereas both kidneys had reductions in absolute [Na.sup.+] excretion and urine flow. Respiratory functional variable were not different between all groups. Therefore, 2 h unilateral renal ischemia and 24 h reperfusion did not affect lung but had distant effects on contralateral kidney partly mediated by ROS and NO-derived from iNOS to dampen compensatory increases in renal hemodynamics and to decrease tubular reabsorption. Key words: acute kidney injury, acute lung injury, alpha-tocopherol, aminoguanidine, inducible nitric oxide synthase, ischemia/ reperfusion, reactive oxygen species, unilateral nephrectomy, unilateral renal ischemia. Le dommage renal aigu est normalement associe a un dysfonctionnement d'organes situes a distance. Les roles de la synthase d'oxyde nitrique inductible (iNOS) et des especes reactives d'oxygene (ERO) dans ce phenomene ont ete examines a la suite d'une ischemie unilaterale renale de 2 h et d'une reperfusion de 24 h. Trois groupes de rats ont ete soumis soit, a une ischemie/reperfusion unilaterale (groupe IRU), soit a une nephrectomie unilaterale (NXU) ou a une operation fictive. Deux autres groupes ont recu de l'α-tocopherol et de l'aminoguanidine en plus de l'IRU (groupe IRU traite) ou la NXU (groupe NXU traite). Le rapport nitrite/nitrate plasmatique et les niveaux de malonaldehyde etaient eleves chez le groupe IRU seulement. La clairance de la creatine et le debit sanguin augmentaient dans le rein non-ischemique du groupe IRU, mais dans une ampleur moindre que dans le rein restant du groupe NXU, alors qu'ils presentaient des augmentations compensatoires egales sur le plan de l'excretion absolue de [Na.sup.+] et de [K.sup.+] et du debit urinaire. L'augmentation du debit sanguin etait plus importante dans le rein non-ischemique du groupe IRU traite, contrairement au rein restant du groupe NXU traite, alors que l'excretion absolue de [Na.sup.+] et le debit urinaire etaient reduits dans les deux types de reins. Les variables respiratoires fonctionnelles n'etaient pas differentes entre tous les groupes. Ainsi, une ischemie renale unilaterale de 2 h et une reperfusion de 24 n'affectent pas le poumon mais exercent des effets a distance sur le rein contra-lateral medies en partie par les ERO et le NO produit par la iNOS afin d'attenuer les augmentations compensatoires dans l'hemodynamique renale et de diminuer la reabsorption tubulaire. [Traduit par la Redaction] Mots-cles : dommage renal aigu, dommage pulmonaire aigu, alpha-tocopherol, aminoguanidine, synthase d'oxyde nitrique inductible, ischemie/reperfusion, especes reactives d'oxygene, nephrectomie unilaterale, ischemie renale unilaterale., Introduction Acute kidney injury (AKI) comprises 30%-50% of admissions to critical care units. Despite advances in the renal replacement therapies and intensive care support, patients with AKI still have mortality [...]

Acute respiratory disorders and permissive hypercapnic strategy may lead to alveolar hypoxia and hypercapnic acidosis. However, the effects of hypercapnia with or without acidosis on hypoxic pulmonary vasoconstriction (HPV) and oxygen diffusion capacity of the lung are controversial. We investigated the effects of hypercapnic acidosis and hypercapnia with normal pH (pH corrected with sodium bicarbonate) on HPV, capillary permeability, gas exchange, and ventilation-perfusion matching in the isolated ventilated-perfused rabbit lung. No alteration in vascular tone was noted during normoxic hypercapnia with or without acidosis compared with normoxic normocapnia. Hypercapnia with normal pH resulted in a transient increase in HPV during the course of consecutive ventilation maneuvers, whereas hypercapnic acidosis increased HPV over time. Hypercapnic acidosis decreased exhaled NO during hypoxia more than hypercapnia with normal pH and normocapnia, whereas intravascular NO release was unchanged. However, inhibition of NO synthesis by nitro-L-arginine (L-NNA) resulted in a loss of the increased HPV caused by hypercapnic acidosis but not that caused by hypercapnia with normal pH. Furthermore, capillary permeability increased during hypoxic hypercapnia with normal pH but not hypoxic hypercapnic acidosis. This effect was NO-dependent because it disappeared during L-NNA administration. Ventilation-perfusion matching and arterial Po2 were improved according to the strength of HPV in hypercapnia compared with normocapnia during Tween nebulization-induced lung injury. In conclusion, the increased HPV during hypercapnic acidosis is beneficial to lung gas exchange by improving ventilation-perfusion matching and preserving the capillary barrier function. These effects seem to be linked to NO-mediated pathways. hypoxia; hypercapnic acidosis; pH; capillary permeability doi: 10.1152/ajplung.00074.2009.