Characterization of angiotensin iv degrading enzymes and receptors
on rat mesangial cells.
Dominique_chansel, Stanislas_czekalski, Sophie_vandermeersch, Emmanuel
Ruffet, Marie-Claude_fourni[acute]e-Zaluski and Raymond_ardaillou.
1INSERM 64, H[circumflex]opital Tenon, 75020 Paris, France ; and
2INSERM 266-CNRS UA 498, Universit[acute]e Ren[acute]e Descartes,
75006 Paris, France
APStracts 5:0112F, 1998.
Because mesangial cells (MC) are a target and a degradation site for
angiotensin (Ang) II, we characterized the degrading enzymes and
receptors of Ang IV, a metabolite of Ang II, on these cells. Ang_IV
was metabolized into its N-terminal deleted peptides, Ang_II (4-8),
Ang_II (5-8) and Ang_II (6-8) by rat MC. Total protection of Ang_IV
was obtained only when PC_18, a specific aminopeptidase N (APN)
inhibitor, and JFH27A, a mixed inhibitor of dipeptidylaminopeptidase
(DAP) and neutral endopeptidase (NEP) were simultaneously added. In
contrast, thiorphan, a NEP inhibitor, was inactive. These results
demonstrate the exclusive role of APN and DAP in Ang IV degradation.
[125I]-Ang_IV binding was studied in the presence of PC 18 and JFH27A
to suppress ligand degradation. Under these conditions, Ang IV
specific receptors could be demonstrated with a KD of 1.8 nM and a
density of 55_fmol/mg. In contrast with mesangial cells, no evidence
for Ang IV receptors could be obtained in freshly isolated glomeruli.
Ang IV stimulated cytosolic calcium concentration in MC whereas its
N-deleted metabolites were inactive. Therefore, Ang_IV must be
protected from degradation by APN and DAP in studies on the non
immediate biological effects of this peptide.
Received 29 December 1997; accepted in final form 18 June 1998.
APS Manuscript Number F411-7.
Article publication pending Am. J. Physiol. (Renal Physiology).
ISSN 1080-4757 Copyright 1998 The American Physiological Society.
Published in APStracts on 30 July 1998