Vasoconstrictor PGs activating the TP receptor (R) include PGH2, TxA2 and isoprostanes (Iso). NO or peroxynitrite (ONOO), its reaction product with superoxide anion (02""""""""'), can activate cyclooxygenase (COX) whereas O2""""""""""""""""and ONOO can inactivate prostacyclin synthase (PGIz-S), activate TxAz synthase and generate Iso, thereby promoting vasoconstrictor PG mechanisms. The specific roles of COX-1 vs. -2, and the diverse agonists of the TP-R and their role in the regulation of microvascular resistance, salt balance and BP remain unclear. This is the focus of this proposal.
Specific Aim I will utilize COX-1 and TP-R gene deleted mice, and specific COX-2 antagonists to investigate the hypothesis that these systems have discrete roles in normal homeostasis by adjusting salt excretion, renal microvascular resistance, tubuloglomerular feedback (TGF) and proximal NaCI reabsorption to stabilize BP and prevent salt sensitivity during changes in salt intake.
Specific Aim II will investigate the hypothesis that neuronal nitric oxide synthase (nNOS)- derived NO generated during macula densa (MD) solute reabsorption activates COX-2 dependent signaling pathway from the MD that regulates afferent arteriolar tone via release of PGH2. PGH2 can be metabolized to vasodilator PG's that limit vasoconstrictor TGF responses, but during Ang II action, PGI2-S is blocked, and PGH2, Iso and TxA2 activate TP-R-dependent enhancement of TGF, thereby assisting in salt and volume preservation.
Specific Aim III will investigate the hypothesis that a COX- and TP-R-dependent process enhances vasoconstriction to Ang II and diminishes vasodUation to acetylcholine of the renal afferent arteriole of mice undergoing an Ang II slow pressor response. These studies are focused on the roles of COX-1 vs. -2, and TP-R in mediating renal mechanism of homeostasis and their dysregulation during Ang II hypertension.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Method to Extend Research in Time (MERIT) Award (R37)
Project #
5R37DK036079-26
Application #
8310800
Study Section
Special Emphasis Panel (NSS)
Program Officer
Ketchum, Christian J
Project Start
1985-07-01
Project End
2014-05-31
Budget Start
2012-06-01
Budget End
2014-05-31
Support Year
26
Fiscal Year
2012
Total Cost
$549,725
Indirect Cost
$191,598
Name
Georgetown University
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
049515844
City
Washington
State
DC
Country
United States
Zip Code
20057
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