Previous studies showed increased extracellular
nucleotides during renal
ischemia-reperfusion. While
nucleotides represent the main source for extracellular
adenosine and
adenosine signaling contributes to renal protection from
ischemia, we hypothesized a role for ecto-
nucleoside-
triphosphate-diphosphohydrolases (E-NTPDases) in renal protection. We used a model of murine
ischemia-reperfusion and in situ ischemic preconditioning (IP) via a hanging weight system for atraumatic renal artery occlusion. Initial studies with a nonspecific inhibitor of E-NTPDases (POM-1) revealed inhibition of renal protection by IP. We next pursued transcriptional responses of E-NTPDases (E-NTPDase1-3, and 8) to renal IP, and found a robust and selective induction of E-
NTPDase1/CD39 transcript and
protein. Moreover, based on clearance studies, plasma
electrolytes, and renal tubular histology, IP protection was abolished in gene-targeted mice for cd39 whereas increased renal
adenosine content with IP was attenuated. Furthermore, administration of
apyrase reconstituted renal protection by IP in cd39-/- mice. Finally,
apyrase treatment of wild-type mice resulted in increased renal
adenosine concentrations and a similar degree of renal protection from
ischemia as IP treatment. Taken together, these data identify CD39-dependent
nucleotide phosphohydrolysis in renal protection. Moreover, the present studies suggest
apyrase treatment as a novel pharmacological approach to renal diseases precipitated by limited
oxygen availability.