Immunolocalisation of adenosine A(1) receptors in the rat kidney

The location of adenosine A(1) receptors in the rat kidney was investigated using immunolabelling with antibodies raised to a 15-amino-acid sequence n ear the C-terminus of the receptor (antibody I) and to a 14-amino-acid sequ ence in the second extracellular loop (antibody II). In the cortex, antibod y I bound to adenosine A(1) receptors in mesangial cells and afferent arter ioles, whilst antibody II bound to receptors in proximal convoluted tubules . In the medulla, both antibodies bound to receptors in collecting ducts an d the papillary surface epithelium. These observations provide support for the diverse functional roles previously proposed for the adenosine A(1) rec eptor in the kidney. The labelling of distinct but different structures in the cortex by antibodies raised to different amino acid sequences on the A( 1) receptor protein suggests that differing forms of the receptor are prese nt in this region of the kidney. (C) 2001 Elsevier Science Inc. All rights reserved.