High phosphate serum levels correlate with the severity of experimental severe acute pancreatitis: insight into the purinergic system

Extracellular purines are a component of the systemic inflammatory response, and their levels are modulated by ectonucleotidases. In addition, nucleotide hydrolysis releases phosphate. We studied serum phosphate levels as a predictor of severity in acute pancreatitis (AP) and their correlation with extracellular purinergic metabolism. Acute pancreatitis was induced by the retrograde injection of sodium taurocholate. The AP group was compared with animals submitted to a model of sepsis by cecal ligation and puncture. The sham group was submitted to laparotomy and closure. We measured the phosphate and purine levels in serum and the expression of 5'-nucleotidase (CD73) and the adenosine A2a receptor in pancreatic tissue by quantitative real-time polymerase chain reaction. Serum phosphate levels were higher in severe AP and correlated with severity. Severe AP led to increased serum levels of adenosine diphosphate, adenosine monophosphate, and adenosine. In addition, adenosine monophosphate conversion to adenosine in serum was accelerated in the AP groups. We found a positive correlation between serum adenosine and phosphate in the AP groups. The expression levels of CD73 and the adenosine A2a receptor in the pancreas were not altered. Our study suggests that serum phosphate correlates with severity in AP and implicates extracellular purines in the systemic response to severe AP.