Abstract P140: Alamandine Signaling in Cardiomyocytes in Health and Disease
Alamandine is a new component of the renin-angiotesin system generated from angiotensin A or angiotensin-(1[[Unable to Display Character: –]]7). Its biological actions include vasodilation, and antihypertensive effects. In the heart, the molecular pathways activated by alamandine have not been characterized. Our goal was to investigate the signaling pathways activated by alamandine in ventricular myocytes isolated from both healthy and hypertensive models. Cardiomyocytes isolated from C57BL/6 mice and from rats that overexpress renin (TGRmRen) were treated with 100nmol/L alamandine. Intracellular nitric oxide (NO) and Ca2+ levels were recorded in cells loaded with DAF-FM and Fluo4-AM, respectively. Protein phosphorylation was assessed by western-blot. In cardiomyocytes, alamandine induced an increase in phosphorylation of PDK1 (arbitrary units (a.u.): control=0,20±0.06 versus alamandine=0,42±0.08 n=6, p<0.05) and Akt Ser473 (a.u.: control= 0,40 ±0,01 versus alamandine= 0,52±0,10 n=5 p<0.05). Moreover, alamandine induced a significant increase in NO (Fluorescence a.u.: control=4.8±0.8 n=44 versus alamandine=12.19±1.47 n=85 p<0.05), without any effect on Ca2+ transient amplitude. Ventricular myocytes treated with alamandine showed decreased GSK3β phosphorylation (a.u.: control=0,62±0.19 versus alamandine=0,50±0.25 n=5 p<0.05) and increased phosphorylation of ERK1/2 (a.u.: control=0,48±0.24 versus alamandine= 0,80±0.29, n=7 p<0.05) when compared to control. Conversely, TGRmRen cardiomyocytes exposed to alamandine showed increased GSK3β phosphorylation and decreased phosphorylation of ERK1/2. The effect of alamandine on Akt phosphorylation was preserved in TGRmRen cardiomyocytes. Furthermore, alamandine treatment prevented both cardiomyocyte hypertrophy (area (μm2): control=447±23 n=58; angiotensin II= 609±26 n=70; angiotensin II+alamandine= 491±31 n=45 p<0.05), and nuclear translocation of GRK5 induced by 100nmol/L angiotensin II. Our data show that alamandine signaling in cardiomyocytes changes according to different pathophysiological condition, and includes the activation of cardioprotective pathways. These data highlight the therapeutic potential of alamandine in the heart.
Author Disclosures: I.C. Jesus: None. S. Scalzo: None. C. Rocha-Resende: None. R.A. Santos: None. S. Guatimosim: None.
- © 2015 by American Heart Association, Inc.