The effect of arachidonic acid on prostaglandin metabolism in rat isolated perf used kidney

Abstract

The purpose of the present study is to assess the effect of arachidonic acid (AA) and renal perfusion perssure on renal prostaglandin (PG) metabolism. The rat isolated blood-free perfused kidney was used. This system has been proven to be a useful tool for studying the renal hormonal metabolism. In the present study, two different perfusion pressures were employed. We assumed the low perfusion pressure (LPP) as an ischemic state of the kidney expecting the increase in prostacyclin production and the high perfusion pressure (HPP) as a physiological state of the kidney. In high perfusion pressure experiments, AA stimulated the perfusate PGE₂, PGF_2α secretions biphasically but perfusate 6-keto-PGF_1α secretion monophasically. In LPP experiments, perfusate 6-keto-PGF_1a increased 6-folds higher than that of HPP experiments. There was no difference in perfusate 6-keto-PGF_1α between with AA and without AA experiments in LPP experiments. In HPP experiments, urinary PGE₂, PGF_2α and thromboxane B₂ (TxB₂) excretions were stimulated by AA but urinary 6-keto-PGF_1α excretion was not stimulated by AA. From these results, the following conclusions were obtained. (a) The prostaglandin metabolisms were different between HPP and LPP experiments. (b) The rat isolated blood-free perfused kidney was able to produce TxB₂ and excrete it. (c) 6-keto-PGF_1α showed the different releasing pattern from that of PGE₂, PGF_2α and TxB₂ suggesting different metabolic site and/or releasing mechanism.