Influence of NaCl concentration at the macula densa on angiotensin II-induced constriction of the afferent arteriole

Hypertension
Y L RenS Ito

Abstract

The macula densa, a plaque of specialized tubular epithelial cells, monitors NaCl concentrations in tubular fluid and controls resistance of the glomerular afferent arteriole (AA). In vivo micropuncture studies suggest that there are significant interactions between angiotensin II (Ang II) and macula densa control of glomerular hemodynamics. We tested the hypothesis that Ang II causes stronger constriction of the AA when NaCl concentration at the macula densa is elevated. Rabbit AAs and the attached macula densa were simultaneously microperfused in vitro, and dose-response curves to Ang II were obtained when the macula densa was not perfused or was perfused with either low NaCl (Na+, 26 mEq/L; Cl-, 7 mEq/L) or high NaCl (Na+, 84 mEq/L; Cl-, 65 mEq/L). Ang II induced stronger constriction when the macula densa was perfused with high NaCl; the decrease in diameter at 100 pmol/L was 29 +/- 5.6% (n= 7) compared with 2.1 +/- 1.2% (n=8) for the nonperfused macula densa or 6.1 +/- 4.2% (n=7) for low NaCl (P < .002). However, there was no such difference in the action of norepinephrine. Adding furosemide (10 micromol/L) to the macula densa perfusate abolished the difference in Ang II action between low and high NaCl at the macula densa...Continue Reading

Citations

Jan 3, 2001·Kidney International·Y RenO A Carretero
Sep 13, 2003·Kidney International·Yilin RenJeffrey L Garvin
Jul 1, 1997·Clinical and Experimental Pharmacology & Physiology·S Ito, K Abe
Jan 14, 2003·Annual Review of Physiology·P Darwin BellJános Peti-Peterdi
Aug 22, 2008·American Journal of Physiology. Renal Physiology·YiLin RenOscar A Carretero
Dec 17, 2009·Clinical and Experimental Hypertension : CHE·Yoshiro NaitoTohru Masuyama
Jul 12, 2002·Kidney International·YiLin RenJeffrey L Garvin
Apr 1, 1997·The Tohoku Journal of Experimental Medicine·S Ito
Jan 13, 2004·American Journal of Physiology. Regulatory, Integrative and Comparative Physiology·Charlotte Mehlin SorensenNiels-Henrik Holstein-Rathlou

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