Renal cortical cyclooxygenase 2 expression is differentially regulated by angiotensin II AT(1) and AT(2) receptors

• Published in: Proceedings of the National Academy of Sciences - PNAS 2006-10, Vol.103 (43), p.16045-16050
• Main Authors: Zhang, Ming-Zhi, Yao, Bing, Cheng, Hui-Fang, Wang, Su-Wan, Inagami, Tadashi, Harris, Raymond C
• Format: Article
• Language: English
• Subjects: Angiotensin II - biosynthesis; Angiotensin II Type 2 Receptor Blockers; Animals; Bradykinin - pharmacology; Cell Line; Cyclooxygenase 2 - genetics; Cyclooxygenase 2 - metabolism; Gene Expression Regulation, Enzymologic - drug effects; Kidney Cortex - drug effects; Kidney Cortex - metabolism; Male; Mice; Mice, Knockout; Nitric Oxide Synthase Type I - metabolism; Rats; Receptor, Angiotensin, Type 1 - deficiency; Receptor, Angiotensin, Type 1 - genetics; Receptor, Angiotensin, Type 1 - metabolism; Receptor, Angiotensin, Type 2 - deficiency; Receptor, Angiotensin, Type 2 - genetics; Receptor, Angiotensin, Type 2 - metabolism; Sodium-Potassium-Chloride Symporters - metabolism; Solute Carrier Family 12, Member 1
• ISSN: 0027-8424
• DOI: 10.1073/pnas.0602176103

Macula densa cyclooxygenase 2 (COX-2)-derived prostaglandins serve as important modulators of the renin-angiotensin system, and cross-talk exists between these two systems. Cortical COX-2 induction by angiotensin-converting enzyme (ACE) inhibitors or AT(1) receptor blockers (ARBs) suggests that angiotensin II may inhibit cortical COX-2 by stimulating the AT(1) receptor pathway. In the present studies we determined that chronic infusion of either hypertensive or nonhypertensive concentrations of angiotensin II attenuated cortical COX-2. Angiotensin II infusion reversed cortical COX-2 elevation induced by ACE inhibitors. However, we found that angiotensin II infusion further stimulated cortical COX-2 elevation induced by ARBs, suggesting a potential role for an AT(2) receptor-mediated pathway when the AT(1) receptor was inhibited. Both WT and AT(2) receptor knockout mice were treated for 7 days with either ACE inhibitors or ARBs. Cortical COX-2 increased to similar levels in response to ACE inhibition in both knockout and WT mice. In WT mice ARBs increased cortical COX-2 more than ACE inhibitors, and this stimulation was attenuated by the AT(2) receptor antagonist PD123319. In the knockout mice ARBs led to significantly less cortical COX-2 elevation, which was not attenuated by PD123319. PCR confirmed AT(1a) and AT(2) receptor expression in the cultured macula densa cell line MMDD1. Angiotensin II inhibited MMDD1 COX-2, and CGP42112A, an AT(2) receptor agonist, stimulated MMDD1 COX-2. In summary, these results demonstrate that macula densa COX-2 expression is oppositely regulated by AT(1) and AT(2) receptors and suggest that AT(2) receptor-mediated cortical COX-2 elevation may mediate physiologic effects that modulate AT(1)-mediated responses.