Effect of intrarenal adenosine on urinary excretion of prostaglandins and leukotrienes in the anesthesized dog

Adenosine is a renal vasoconstrictor that plays an important role in mediating renal adaptive responses to decreases in renal perfusion pressure. It is known that adenosine acts on the metabolism of arachidonic acid, but the direct repercussions of adenosine in the production of renal prostaglandins and leukotrienes have not been studied. This study was undertaken to evaluate the effect of the intrarenal infusion of adenosine upon the urinary elimination of arachidonic acid derivatives. Samples of urine were collected with lysine acetylsalicylate and determination of prostaglandins (PGs) and leukotrienes (LTs) was performed by radioimmunoassay of samples previously separated by HPLC. The infusion of adenosine decreases the urinary excretion of 6-keto-PGF1 alpha and TxB2 significantly. There was no significant change in urinary excretion of PGE2 while LTB4 and LTC4 showed a tendency to increase. These results suggest that a fall in the synthesis of PGI2 along with an increase in LTC4, which is a constrictor of mesangial cells, could be responsible for the renal vasoconstriction phase of adenosine. Therefore, it was concluded that adenosine vasoconstriction is mediated through the inhibition of the cyclo-oxygenase pathway, diminishing the synthesis of PG vasodilators.