• Stephan W Reinhold, Bernd Krüger, Caroline Barner, Flavius Zoicas, Martin C Kammerl, Ute Hoffmann, Tobias Bergler, Bernhard Banas, and Bernhard K Krämer.
• Klinik und Poliklinik für Innere Medizin II, University of Regensburg, Regensburg, Germany.
• J Renin Angiotensin Aldosterone Syst. 2012 Mar 1; 13 (1): 46-55.

IntroductionThe renin-angiotensin-aldosterone system (RAAS) plays an integral role in the regulation of blood pressure, electrolyte and fluid homeostasis in mammals. The capability of the different nephron segments to form components of the RAAS is only partially known. This study therefore aimed to characterize the nephron-specific expression of RAAS components within the mouse kidney.Materials And MethodsDefined nephron segments of adult C57B/16 mice were microdissected after collagenase digestion. The gene expression of renin, angiotensinogen (AGT), angiotensin-converting enzyme (ACE), angiotensin II receptors 1a (AT1a), 1b (AT1b), and 2 (AT2) was assessed by reverse transcriptase polymerase chain reaction (RT-PCR).ResultsRenin mRNA was present in glomeruli, in proximal tubules, in distal convoluted tubules (DCT) and cortical collecting ducts (CCD). AGT mRNA was found in proximal tubules, descending thin limb of Henle's loop (dTL) and in the medullary part of the thick ascending limb (mTAL). ACE mRNA was not detectable in microdissected mouse nephron segments. AT1a, AT1b and AT2 mRNA was detected in glomeruli and proximal convoluted tubules.ConclusionsOur data demonstrate a nephron-specific distribution of RAAS components. All components of the local RAAS - except ACE - are present in proximal convoluted tubules, emphasizing their involvement in sodium and water handling.

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