A scrutiny of the biochemical pathways from Ang II to Ang-(3–4) in renal basolateral membranes

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• 作者：Flavia Axelb ; Juliana Dias ; Filipe Mir ; a ; Fern ; a M. Ferrã ; o ; Nilana M. Barros ; Adriana K. Carmona ; Lucienne S. Lara ; Adalberto Vieyra
• 关键词：Ang-(3– ; 4) ; Plasma membrane Ca²⁺-ATPase ; Peptidases ; Angiotensin metabolism ; Kidney cells ; Basolateral membranes
• 刊名：Regulatory Peptides
• 出版年：2009
• 出版时间：27 November 2009
• 年：2009
• 卷：158
• 期：1-3
• 页码：47-56
• 全文大小：1172 K

文摘

In a previous paper we demonstrated that Ang-(3–4) counteracts inhibition of the Ca²⁺-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 II 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). Ca²⁺-ATPase assays with different Ang II concentrations and different peptidase inhibitors confirm the existence of these pathways in BLM and show that a prolyl-carboxypeptidase 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 Ca²⁺-ATPase, enabling a local RAS axis to effect rapid modulation of active Ca²⁺ fluxes.