Alamandine enhances cardiomyocyte contractility in hypertensive rats through a nitric oxide-dependent activation of CaMKII

Abstract

Overstimulation of the renin-angiotensin system (RAS) has been implicated in the pathogenesis of various cardiovascular diseases. Alamandine is a peptide newly identified as a protective component of the RAS; however, the mechanisms involved in its beneficial effects remain elusive. By using a well-characterized rat model of hypertension, the TGR (mREN2)27, we show that mREN ventricular myocytes are prone to contractile enhancement mediated by short-term alamandine (100 nmol/L) stimulation of Mas-related G protein-coupled receptor member D (MrgD) receptors, while Sprague-Dawley control cells showed no effect. Additionally, alamandine prevents the Ca2+ dysregulation classically exhibited by freshly isolated mREN myocytes. Accordingly, alamandine treatment of mREN myocytes attenuated Ca2+ spark rate and enhanced Ca2+ reuptake to the sarcoplasmic reticulum. Along with these findings, KN-93 fully inhibited the alamandine-induced increase in Ca2+ transient magnitude and phospholamban (PLN) phosphorylation at Thr17, indicating CaMKII as a downstream effector of the MrgD signaling pathway. In mREN ventricular myocytes, alamandine treatment induced significant nitric oxide (NO) production. Importantly, NO synthase inhibition prevented the contractile actions of alamandine, including PLN-Thr17 phosphorylation at the CaMKII site, thereby indicating that NO acts upstream of CaMKII in the alamandine downstream signaling. Altogether, our results show that enhanced contractile responses mediated by alamandine in cardiomyocytes from hypertensive rats occur through a NO-dependent activation of CaMKII.

Dense optical flow software to quantify cellular contractility

“…An important parameter for the analysis of the isolated CM is contractility, which provides information that reflects its cellular function. Measurements of contractility have been widely used for research on both adult and neonatal myocytes ( Belostotskaya and Golovanova, 2014 ; Berger et al., 1994 ; Boudreau-Béland et al., 2015 ; Harary and Farley, 1960 ; Haworth et al., 1987 ; Hissa et al., 2017 ; Jesus et al., 2020 ; Penitente et al., 2014 ; Ramadan et al., 2018 ). More recently, human induced pluripotent stem cell-derived CMs (hiPSC-CMs) have been employed as a model for human cardiac disease and drug screening ( Ballan et al., 2020 ; Birket et al., 2015 ; Gong and Sobie, 2018 ; Lahti et al., 2012 ; Lan et al., 2013 ; Ribeiro et al., 2015 ; Wang et al., 2014 , 2019 ).…”

CaMKIIδ Splice Variants in the Healthy and Diseased Heart

“…However, even though there are no studies on the physiological functions of CaMKIIδC specifically, it likely is the splice isoform that precisely modulates intracellular Ca 2+ handling in ECC and ETC ( Maier and Bers, 2007 ; Bers, 2011 ) and the heart rate in fight or flight response ( Wu et al, 2009 ), suggesting that CaMKIIδC is also needed for normal heart function. In addition, the response of cardiomyocytes to the adaptive stimuli Insulin-like growth factor 1, exercise, or the vasoactive peptide alamandine show the dependence of positive effects on Ca 2+ cycling and contractility on CaMKII activity ( Beckendorf et al, 2018 ; Jesus et al, 2020 ). Therefore, also with this splice isoform, the question remains when it is detrimental and when it is not.…”

The Network of Angiotensin Receptors in Breast Cancer

“…Alamandine was also reported to induce the activation of the adenosine monophosphate kinase (AMPK) pathway [ 7 ], to inhibit the MAPK signaling pathways [ 21 ] and to activate Jun- N -terminal kinase (JNK) phosphorylation to inhibit the nuclear factor κB (NF-κB) signaling pathway [ 22 ]. Alamandine-dependent stimulation of NO via MRGD also determines the activation of calcium/calmodulin-dependent protein kinase II (CaMKII) [ 23 ]. Interestingly, the differential activation of the different pathways is cell type-specific and has been observed in adipose tissue and adipose tissue cells as well as in different cellular models of the cardiovascular apparatus [ 19 ].…”