Calhex231 Ameliorates Cardiac Hypertrophy by Inhibiting Cellular Autophagy in Vivo and in Vitro

Abstract

Background/Aims: Intracellular calcium concentration ([Ca²⁺]_i) homeostasis, an initial factor of cardiac hypertrophy, is regulated by the calcium-sensing receptor (CaSR) and is associated with the formation of autolysosomes. The aim of this study was to investigate the role of Calhex₂₃₁, a CaSR inhibitor, on the hypertrophic response via autophagy modulation. Methods: Cardiac hypertrophy was induced by transverse aortic constriction (TAC) in 40 male Wistar rats, while 10 rats underwent a sham operation and served as controls. Cardiac function was monitored by transthoracic echocardiography, and the hypertrophy index was calculated. Cardiac tissue was stained with hematoxylin and eosin (H&E) or Masson's trichrome reagent and examined by transmission electron microscopy. An angiotensin II (Ang II)-induced cardiomyocyte hypertrophy model was established and used to test the involvement of active molecules. Intracellular calcium concentration ([Ca²⁺]_i) was determined by the introduction of Fluo-4/AM dye followed by confocal microscopy. The expression of various active proteins was analyzed by western blot. Results: The rats with TAC-induced hypertrophy had an increased heart size, ratio of heart weight to body weight, myocardial fibrosis, and CaSR and autophagy levels, which were suppressed by Calhex₂₃₁. Experimental results using Ang II-induced hypertrophic cardiomyocytes confirmed that Calhex₂₃₁ suppressed CaSR expression and downregulated autophagy by inhibiting the Ca²⁺/calmodulin-dependent-protein kinase-kinase-β (CaMKK_β)- AMP-activated protein kinase (AMPK)-mammalian target of rapamycin (mTOR) pathway to ameliorate cardiomyocyte hypertrophy. Conclusions: Calhex₂₃₁ ameliorates myocardial hypertrophy induced by pressure-overload or Ang II via inhibiting CaSR expression and autophagy. Our results may support the notion that Calhex₂₃₁ can become a new therapeutic agent for the treatment of cardiac hypertrophy.

Stachydrine Protects Against Pressure Overload-Induced Cardiac Hypertrophy by Suppressing Autophagy

“…Nakai et al reported that cardiomyocytes manifest a classical hypertrophic response with a reduced autophagic activity [11], while Kanamori et al reported that during nutrient deprivation, suppressed autophagy leads to reduced cardiac ATP content and impaired heart performance [12]. Furthermore, studies with human samples and pressure overload animal models have suggested that excessive autophagy activity may play a maladaptive role in heart failure pathogenesis [13-17]. In the present study, we found excessive autophagy activity in the myocardium of animals subjected to the TAC operation, correlated with myocardium hypertrophy and cardiac dysfunction.…”

The vascular Ca2+-sensing receptor regulates blood vessel tone and blood pressure

“…The observed cardiac remodeling, i.e., stronger mode of contraction, together with the increase in dp/dt, could thus be interpreted as compensatory response to the bradycardic and hypotensive phenotype. The reduction in fibrosis suggests that KO animals might be protected against the development of age-related cardiac fibrosis (2), maybe via a beneficial effect of their reduced heart rate (8) but could also be a direct consequence of CaSR deletion from the heart, as recently indicated in a rat model of cardiac hypertrophy (32). Further studies will be necessary to completely elucidate the role of the cardiac CaSR.…”

The role of autophagy in angiotensin II-induced pathological cardiac hypertrophy

“…Many signaling pathways have also been found to be involved in Ang II-induced autophagy, for example, Calhex231 suppressed calcium-sensing receptor (CaSR) expression and downregulated autophagy by inhibiting the Ca 2+ /calmodulin-dependent protein kinase-kinase-β (CaMKKβ)-AMPK-mTOR pathway to ameliorate cardiomyocyte hypertrophy induced by Ang II in neonatal rat cardiomyocytes (Liu et al 2015). Ang II exposure induced significant increase in the expression of endogenous intermedin in H9c2 cell cultures and mouse hearts, and the sizes of cardiomyocyte, interstitial collagen, ANP and BNP expression were also increased.…”