Impairment of renal blood flow after renal ischaemia–reperfusion is not aggravated by low plasma levels of arginine

Abstract

Abstract Background The fundamental role of the l-arginine–nitric oxide pathway has not been established for maintaining renal blood flow. Plasma levels of arginine appear to be rate limiting for nitric oxide synthesis in various cell types. Low plasma levels of arginine are seen after major surgery, trauma and sepsis. The present study was designed to establish the effects of low arginine plasma levels on renal blood flow during the initial phase of renal ischaemia–reperfusion. Methods In this unilateral renal ischaemia–reperfusion model, male Wistar rats were used. Arginase infusion (ASE) was used to lower arginine plasma levels to 50 per cent of normal; control rats received saline infusion (SAL). After an ischaemic period of 90 min, the kidney was perfused for 150 min (IR kidney). The contralateral kidney was left in situ and served as a control (CL kidney). Blood flow measurement was performed at the end of the experiment using radiolabelled microspheres. Blood samples were taken for amino acid analysis (high-pressure liquid chromatography). Results Infusion of arginase efficiently decreased plasma levels of arginine (ASE mean(s.d.) 45·3(4·8) μmol/dm3 versus SAL 107·5(6·0) μmol/dm3; P < 0·0001). In both SAL and ASE rats, a significantly lower blood flow was found in the IR kidney compared with the (non-ischaemic) CL kidney. Lowering arginine plasma levels by arginase did not influence renal blood flow compared with SAL, in both IR and CL kidneys. Conclusion In this acute, unilateral renal ischaemia–reperfusion model, low arginine plasma levels did not further aggravate renal blood flow.