The pathophysiology of contrast-induced AKI (CIAKI) is incompletely understood due to the lack of an appropriate in vivo model that demonstrates reduced kidney function before administration of
radiocontrast media (RCM). Here, we examine the effects of CIAKI in vitro and introduce a murine
ischemia/reperfusion injury (IRI)-based approach that allows induction of CIAKI by a single intravenous application of standard RCM after injury for in vivo studies. Whereas murine renal tubular cells and freshly isolated renal tubules rapidly absorbed RCM, plasma membrane integrity and cell viability remained preserved in vitro and ex vivo, indicating that RCM do not induce apoptosis or regulated
necrosis of renal tubular cells. In vivo, the IRI-based CIAKI model exhibited typical features of clinical CIAKI, including RCM-induced osmotic
nephrosis and increased serum levels of
urea and
creatinine that were not altered by inhibition of apoptosis. Direct evaluation of renal morphology by intravital microscopy revealed dilation of renal tubules and peritubular capillaries within 20 minutes of RCM application in uninjured mice and similar, but less dramatic, responses after IRI pretreatment.
Necrostatin-1 (Nec-1), a specific inhibitor of the receptor-interacting
protein 1 (RIP1)
kinase domain, prevented osmotic
nephrosis and CIAKI, whereas an inactive Nec-1 derivate (Nec-1i) or the pan-
caspase inhibitor zVAD did not. In addition, Nec-1 prevented RCM-induced dilation of peritubular capillaries, suggesting a novel role unrelated to cell death for the RIP1
kinase domain in the regulation of microvascular hemodynamics and pathophysiology of CIAKI.