Abstract-Previous studies have shown that chronic salt loading increased renal interstitial adenosine concentrations and desensitized renal effects of adenosine, a phenomenon that could facilitate sodium excretion. However, the mechanisms responsible for the increased adenosine production and decreased adenosine response are poorly understood. This study examined the effects of the dietary high salt intake on adenosine metabolism and receptor expression in the renal cortex and medulla in Sprague Dawley rats. Fluorescent high-performance liquid chromatography analyses were performed to determine adenosine levels in snap-frozen kidney tissues. Comparing rats fed a normal (1% NaCl) versus high salt (4% NaCl) diet, renal adenosine concentrations in rats fed a high salt diet were significantly higher Key Words: adenosine Ⅲ 5Ј-nucleotidase Ⅲ adenosine deaminase Ⅲ salt intake Ⅲ kidney Ⅲ isoelectric focusing Ⅲ gel electrophoresis T he role of adenosine in the regulation of renal vascular tone and tubular function has been studied extensively. Adenosine produces a prompt, transient fall in renal blood flow and a decrease in glomerular filtration rate (GFR) when infused into the renal artery. It has been reported that the adenosine-induced decrease in GFR is associated with a fall in glomerular hydrostatic pressure resulting from preglomerular vasoconstriction and postglomerular vasodilation. 1,2 Adenosine A 1 receptor mediates preglomerular vasoconstriction, and A 2 receptor mediates postglomerular vasodilation. [1][2][3][4] Infusion of adenosine into the renal artery also produces diuresis and natriuresis in rats. 5 Micropuncture studies have indicated that adenosine inhibits sodium reabsorption in the loop of Henle. 6 With the use of isolated, perfused tubules and cultured tubular cell lines, adenosine has been reported to alter ion transport in the collecting duct 7,8 or the thick ascending limb, 9 indicating that adenosine may have a direct effect on tubules. Moreover, adenosine increases medullary blood flow, which also plays an important role in mediating the diuresis and natriuresis. 10