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Jens Randel Nyengaard

Up- and down-regulation of angiotensin II AT1-A and AT1-B receptors in afferent and efferent rat kidney arterioles

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  • Stereological Research Laboratory
INTRODUCTION: The contractile effect of angiotensin II via AT(1) receptors on the kidney arterioles is a crucial element in the kidney microcirculation.Angiotensin II also plays a role as an inhibitor via the AT(1) receptors in the renin granulation of the arterioles.We have previously demonstrated that the AT(1) receptors are downregulated in the renin-positive smooth muscle cells (SMCs) in contrast to renin-negative SMCs. In this study, we estimated the numbers of the AT(1) receptor sub-types separately in the afferent and efferent arterioles and the renin-positive and renin-negative SMCs. METHODS: The immunohistochemical signals of theAT(1)-A and AT(1)-B receptors were counted by stereological methods.(1) RESULTS: The number of AT(1)-B receptors in the efferent arterioles (expressed in signals/Amicrom( 3); mean (CV): 0.32 (0.33)) was significantly higher (78%; p<0.05) as compared with the number in the afferent arterioles (0.18 (0.11)). No differences were found in the AT(1)-A receptors. In a number ofAT( 1)-A receptors, significant differences (p<0.01) were detected between the afferent arteriolar renin-positive SMCs (0.13 (0.36)) and the number in renin-negative SMCs (0.25 (0.34)).The AT(1)-B receptors did not display any differences. CONCLUSIONS: These results indicate that the AT(1) receptor sub-types are regulated independently in the SMCs of the normal kidney arterioles.
Original languageEnglish
JournalJournal of the Renin-Angiotensin-Aldosterone System
Pages (from-to)196-201
Number of pages5
Publication statusPublished - 2008

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