Effects of exercise training on excitation-contraction coupling, calcium dynamics and protein expression in the heart of the Neotropical fish Brycon amazonicus

Activation of the cannabinoid type 2 (CB2) receptor improves cardiac contractile performance in fish, Brycon amazonicus

In addition to their well-known classical effects, cannabinoid CB1 and CB2 receptors have also been involvement in both deleterious and protective actions on the heart under various pathological conditions. While the potential therapeutic applications of the endocannabinoid system in the context of cardiovascular function are indeed a viable prospect, significant debate exists within the literature regarding whether CB1, CB2, or a combination of both receptors exert a favorable influence on cardiac function. Hence, the aim of this study was to investigate the effects of CB1 + CB2 or CB2 agonists on cardiac excitation-contraction (E-C) coupling, utilizing fish (Brycon amazonicus) as an experimental model. The CB2 agonist elicited marked positive inotropic and lusitropic responses in isolated ventricular myocardium, induced cyclic adenosine 3',5'-monophosphate (cAMP) production, and upregulated critical Ca2+ handling proteins, such as sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) and Na+/Ca2+ exchanger (NCX). Our current study demonstrated, for the first time, that CB2 receptor activation-induced effects improved the efficiency of Ca2+ cycling, excitation-contraction coupling (E-C coupling), and cardiac performance in under physiological conditions. Hence, CB2 receptors could be considered a potential therapeutic target for modulating cardiac contractile dysfunctions.

Recent advances in mechanistic studies of heart failure with preserved ejection fraction and its comorbidities-Role of microRNAs

BACKGROUND

Heart failure with preserved ejection fraction (HFpEF) is a multifaceted syndrome with a complex aetiology commonly associated with comorbidities such as diabetes mellitus, obesity, hypertension and renal disease. Various diseases induce systemic, chronic and low-grade inflammation; microvascular dysfunction; metabolic stress; tissue ischemia; and fibrosis, leading to HFpEF. An effective treatment for HFpEF is lacking, largely owing to its pathophysiological heterogeneity. Recent studies have revealed that microRNAs (miRNAs) play crucial roles in regulating the pathogenesis of HFpEF and its comorbidities.

METHODS

This narrative review included original articles and reviews published over the past 20 years found through 'PubMed' and 'Web of Science'. The search terms included "HFpEF," "MicroRNAs," "comorbidities," "Microvascular Dysfunction (MVD)," "inflammation," "pathophysiology," "endothelial dysfunction," "energy metabolism abnormalities" "cardiac fibrosis" and "treatment."

RESULTS

Inflammation, MVD, abnormal energy metabolism, myocardial hypertrophy and myocardial fibrosis are important pathophysiological mechanisms underlying HFpEF. As gene expression regulators, miRNAs may contribute to the pathophysiology of HFpEF and are expected to serve in the stratification of patients with HFpEF and as prognostic indicators for monitoring treatment responses.

CONCLUSIONS

A customized strategy based on miRNAs has emerged as an effective treatment for HFpEF. In this review, we discuss recent research surrounding miRNAs and HFpEF and propose potential miRNA targets for the pathophysiology of HFpEF and its comorbidities. Although current research concerning miRNAs and their therapeutic potential is in its early stages, miRNA-based diagnostics and therapeutics hold great promise in the future.