Abstract P411: Angiotensin-(1-7) Preserves Mitochondrial Function in Doxorubicin-exposed Renal Epithelial Cells

Abstract

We recently identified components of an Angiotensin-(1-7) system (Ang7) within mitochondria (Mito) of the renal cortex, as well as angiotensinogen uptake and trafficking to the Mito and nucleus in proximal tubules. Although activation of the Ang II-AT1 receptor (AT1R) axis is deleterious to the Mito, the functional role of Ang7 is unknown. Thus, we evaluated the effects of Ang7 and its agonist AVE0991 (AVE) to attenuate doxorubicin (DOX)-induced Mito toxicity. NRK-52 renal epithelial cells were exposed to DOX (10 μM, 24 hours) and either saline, Ang7 (100 nM), AVE (100 nM), the MasR antagonist A779 (10 μM) or LNAME (1 mM). Mito function in NRK cells was evaluated by a Seahorse XF-96 analyzer; the OCR data were expressed as the mean ± SD. Both Ang7 and AVE attenuated the decline in Mito function by DOX exposure (Fig_A); the calculated maximal respiration (MR) rates for Ang7 and AVE treated DOX cells were similar to control cells without DOX [25.5 ± 4.4 and 26.7 ± 7.8 vs. 33.9 ± 11.4 pmol/min; p>0.05]. Preservation of Mito function by Ang7 and AVE in DOX cells was reversed by the A779 antagonist (Fig_B). Ang7 stimulation of the nitric oxide synthase (NOS)-NO pathway is a key signaling event in various cell types; however, the NOS inhibitor LNAME failed to block the Ang7 response in DOX exposed cells [MR: 32.2 ± 7.6 pmol/min; Fig_B]. DOX also increased phospho-ERK1/2 over 10-fold [1.12 ±. 0.27 vs. 0.08 ± 0.03], but Ang7 did not attenuate the MAPK response [1.19 ±. 0.34]. We conclude that Ang7 preserves mitochondrial function following DOX exposure in tubular epithelial cells. Moreover, the protective effect of the Ang7-MasR axis does not apparently reflect the contribution of the NOS-NO or MAPK pathways.