Purpose of Review Acute Kidney Injury (AKI) is a major clinical problem without effective therapy. Development of AKI among hospitalized patients drastically increases mortality, and morbidity. With increases in complex surgical procedures together with a growing elderly population, the incidence of AKI is rising. Renal adenosine receptor (AR) manipulation may have great therapeutic potential in mitigating AKI. In this review, we discuss renal AR biology and potential clinical therapies for AKI. Recent Findings The 4 AR subtypes (A1AR, A2AAR, A2BAR and A3AR) have diverse effects on the kidney. The pathophysiology of AKI may dictate the specific AR subtype activation needed to produce renal protection. The A1AR activation in renal tubules and endothelial cells produces beneficial effects against ischemia and reperfusion (IR) injury by modulating metabolic demand, decreasing necrosis, apoptosis and inflammation. The A2AAR protects against AKI by modulating leukocyte-mediated renal and systemic inflammation whereas the A2BAR activation protects by direct activation of renal parenchymal ARs. In contrast, the A1AR antagonism may play a protective role in nephrotoxic AKI and radiocontrast induced nephropathy by reversing vascular constriction and inducing naturesis and diuresis. Furthermore, as the A3AR-activation exacerbates apoptosis and tissue damage due to renal IR, selective A3AR antagonism may hold promise to attenuate renal IR injury. Finally, renal A1AR activation also protects against renal endothelial dysfunction caused by hepatic IR injury. Summary Despite the current lack of therapies for the treatment and prevention of AKI, recent research suggests that modulation of renal ARs holds promise in treating AKI and extrarenal injury.

Yap S, Park SW, Egan B, Lee HT. Cytokine elevation and transaminitis after laparoscopic donor nephrectomy. Am J Physiol Renal Physiol 302: F1104 -F1111, 2012. First published January 18, 2012 doi:10.1152/ajprenal.00543.2011.-Acute kidney injury frequently occurs in the critically ill and often progresses into multiorgan dysfunction syndrome, resulting in high mortality. We previously showed that nephrectomized mice had increased interleukin (IL)-6 and tumor necrosis factor (TNF)-␣ that directly contributed to systemic inflammation and hepatic injury. In this study, we examined whether patients undergoing laparoscopic donor nephrectomy have increased postoperative cytokine levels with injury to the liver and whether the remaining kidney sustains injury. Serial serum and urine samples were collected from 32 patients undergoing laparoscopic donor nephrectomy and 17 patients undergoing nonrenal laparoscopic surgery. Serum IL-6, IL-18, TNF-␣ and monocyte chemotactic protein-1 (MCP-1) (markers of systemic inflammation) and urinary neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), MCP-1, and IL-18 (markers of acute kidney injury) were quantified by enzyme-linked immunosorbent assay. We also analyzed serum creatinine, aspartate transaminase (AST), and alanine transaminase to assess liver injury. Patients who underwent donor nephrectomy not only demonstrated increased serum creatinine but also had significant increases in serum IL-6, MCP-1, and AST. Serum TNF-␣ also trended upward in donor nephrectomy patients. Finally, the donor nephrectomy group showed increased urinary NGAL but not KIM-1 at 24 h. Taken together, our findings of increased serum IL-6, MCP-1, and AST after donor nephrectomy suggest that an acute reduction of kidney function induces systemic inflammation and may have distant effects on the liver. Further studies are needed to correlate increased urinary NGAL after donor nephrectomy both as a potential marker for renal tubular stress and/or hypertrophy in the contralateral kidney.acute kidney injury; interleukin-6; neutrophil gelatinase-associated lipocalin; tumor necrosis factor-␣ ACUTE KIDNEY INJURY (AKI) is a frequent occurrence in the critically ill with 5% to 20% of patients experiencing an episode of AKI during their intensive care unit stay (46). Mortality in critically ill patients with AKI remains high and is estimated to be Ͼ50% (54). Even when controlled for the severity of illness, AKI confers an independent risk for mortality regardless of whether AKI is mild or treated with renal replacement therapy (30). Hence, understanding the specific extrarenal effects of AKI in propagating or exacerbating multiorgan dysfunction is essential, since it may lead to new therapies in decreasing mortality after AKI.In animal models, it is increasingly clear that AKI is not an isolated event and induces distant organ dysfunction to the lungs, heart, liver, and brain through a mechanism that involves neutrophil migration and elevated cytokine levels (14).In particular, hepat...

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