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|Title:||A scrutiny of the biochemical pathways from Ang II to Ang-(3-4) in renal basolateral membranes|
Ferrao, Fernanda M.
Barros, Nilana M. [UNIFESP]
Carmona, Adriana K. [UNIFESP]
Lara, Lucienne S.
Universidade Federal do Rio de Janeiro (UFRJ)
Inst Nacl Ciencia & Tecnol Biol Estrutural & Bioi
Universidade Federal de São Paulo (UNIFESP)
Plasma membrane Ca(2+)-ATPase
|Citation:||Regulatory Peptides. Amsterdam: Elsevier B.V., v. 158, n. 1-3, p. 47-56, 2009.|
|Abstract:||In a previous paper we demonstrated that Ang-(3-4) counteracts inhibition of the Ca(2+)-ATPase by Ang II in the basolateral membranes of kidney proximal tubules cells (BLM). We have now investigated the enzymatic routs by which Ang II is converted to Ang-(3-4). Membrane-bound angiotensin converting enzyme, aminopeptidases and neprilysin were identified using fluorescent substrates. HPLC showed that Plummer's inhibitor but not Z-pro-prolinal blocks Ang if metabolism, suggesting that carboxypeptidase N catalyzes the conversion Ang II -> Ang-(1-7). Different combinations of bestatin, thiorphan, Plummer's inhibitor, Ang II and Ang-(1-5), and use of short proteolysis times, indicate that Ang-(1-7)-> Ang-(1-5)-> Ang-(1-4)-> Ang-(3-4) is a major route. When Ang III was combined with the same inhibitors, the following pathway was demonstrated: Ang III -> Ang IV -> Ang-(3-4). Ca(2+)-ATPase assays with different Ang II concentrations and different peptidase inhibitors confirm the existence of these pathways in BLM and show that a prolylcarboxypeptidase may be an alternative catalyst for converting Ang II to Ang-(1-7). Overall, we demonstrated that BLM have all the peptidase machinery required to produce Ang-(3-4) in the vicinity of the Ca(2+)-ATPase, enabling a local RAS axis to effect rapid modulation of active Ca(2+) fluxes. (C) 2009 Elsevier B.V. All rights reserved.|
|Appears in Collections:||Em verificação - Geral|
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