Cardiac taurine and principal amino acids in right and left ventricles of patients with either aortic valve stenosis or coronary artery disease: the importance of diabetes and gender

Proteomic and metabolomic analyses of the human adult myocardium reveal ventricle-specific regulation in end-stage cardiomyopathies

The left and right ventricles of the human heart are functionally and developmentally distinct such that genetic or acquired insults can cause dysfunction in one or both ventricles resulting in heart failure. To better understand ventricle-specific molecular changes influencing heart failure development, we first performed unbiased quantitative mass spectrometry on pre-mortem non-diseased human myocardium to compare the metabolome and proteome between the normal left and right ventricles. Constituents of gluconeogenesis, glycolysis, lipogenesis, lipolysis, fatty acid catabolism, the citrate cycle and oxidative phosphorylation were down-regulated in the left ventricle, while glycogenesis, pyruvate and ketone metabolism were up-regulated. Inter-ventricular significance of these metabolic pathways was then found to be diminished within end-stage dilated cardiomyopathy and ischaemic cardiomyopathy, while heart failure-associated pathways were increased in the left ventricle relative to the right within ischaemic cardiomyopathy, such as fluid sheer-stress, increased glutamine-glutamate ratio, and down-regulation of contractile proteins, indicating a left ventricular pathological bias.

Metabolomics with gut microbiota analysis of podophyllotoxin-mediated cardiotoxicity in mice based on the toxicological evidence chain (TEC) concept

Podophyllotoxin (PPT) is a lignan isolated from the traditional Chinese medicine Dysosma Versipellis, with significant anti-tumor activity. However, its cardiotoxicity restricts its clinical application. This study aims to investigate the cardiotoxicity of PPT in mice and its underlying mechanisms based on the concept of toxicological evidence chain (TEC). In this study, alterations in body weight, behavior, and the levels of myocardial enzymes and histopathology in mice were observed. Additionally, microbiome and metabolome were integrated to identify potential microorganisms, metabolic markers and major pathways with correlation analysis. The results indicated that PPT induced pathological changes in mice, including weight loss, diarrhea, alopecia and dehydration accompanied by increased levels of serum myocardial enzymes. The results of microbiome showed that PPT altered the gut microbiota composition, changing the abundance of microbial community. The results of metabolome studies indicated total of 55 differential metabolites were involved in glycine, serine, and threonine metabolism, alanine, glutamate, and aspartate metabolism, purine, pyrimidine metabolism, and steroid hormone metabolism. Integrating the results of microbiome and metabolome, it was concluded that PPT remodeled the gut microbiota composition, which in turn modified the gut microbiota metabolism, affecting amino acid metabolisms, nucleotide metabolism, and steroid hormone metabolism in the heart, potentially leading to energy metabolism disorders, apoptosis, and oxidative stress, ultimately inducing cardiotoxicity.

The role of taurine through endoplasmic reticulum in physiology and pathology

Taurine is a sulfur-containing amino acid found in many cell organelles that plays a wide range of biological roles, including bile salt production, osmoregulation, oxidative stress reduction, and neuromodulation. Taurine treatments have also been shown to ameliorate the onset and development of many diseases, including hypertension, fatty liver, neurodegenerative diseases and ischemia-reperfusion injury, by exerting antioxidant, anti-inflammatory, and antiapoptotic effects. The endoplasmic reticulum (ER) is a dynamic organelle involved in a wide range of cellular functions, including lipid metabolism, calcium storage and protein stabilization. Under stress, the disruption of the ER environment leads to the accumulation of misfolded proteins and a characteristic stress response called the unfolded protein response (UPR). The UPR protects cells from stress and helps to restore cellular homeostasis, but its activation promotes cell death under prolonged ER stress. Recent studies have shown that ER stress is closely related to the onset and development of many diseases. This article reviews the beneficial effects and related mechanisms of taurine by regulating the ER in different physiological and pathological states, with the aim of providing a reference for further research and clinical applications.

Cardiac Substrate Utilization and Relationship to Invasive Exercise Hemodynamic Parameters in HFpEF

The authors conducted transcardiac blood sampling in healthy subjects and subjects with heart failure with preserved ejection fraction (HFpEF) to compare cardiac metabolite and lipid substrate use. We demonstrate that fatty acids are less used by HFpEF hearts and that lipid extraction is influenced by hemodynamic factors including pulmonary pressures and cardiac index. The release of many products of protein catabolism is apparent in HFpEF compared to healthy myocardium. In subgroup analyses, differences in energy substrate use between female and male hearts were identified.

Glutamine prevents upregulation of NF-kB signaling and caspase 3 activation in ischaemia/reperfusion-induced testicular damage: An animal model

AIM

Testicular ischaemia/reperfusion (I/R) injury is a major consequence of testicular torsion with possible attendant risk of male infertility. Glutamine, on the other hand, is a known antioxidant with anti-inflammatory potential. The present study evaluated whether or not glutamine would improve I/R-induced testicular injury in torsion/detorsion (T/D). The possible associated mechanisms were also investigated.

METHODS

Wistar rats were randomly allotted into four groups (n = 10); sham-operated, glutamine-treated, T/D, and T/D + glutamine. Testicular torsion was induced and reperfusion established after two and a half hour under ketamine/xylazine anaethesia. Glutamine was administered one hour before reperfusion and continued daily for 3 days. At the end of the study, animals were euthanized, blood samples obtained, epididymal sperm suspension collected, and the testes harvested for biochemical and histopathological assays using established methods.

RESULTS

Glutamine prevented T/D-driven I/R-induced reduced sperm quality, impaired testicular histoarchitecture, and suppressed circulating testosterone. Also, glutamine abated I/R-induced oxidative stress (evidenced by reduced hydrogen peroxide and MDA generation and enhanced concentrations and activities of antioxidants), inflammation (evidenced by suppression of TNF-α and IL-1β), and apoptosis (evidenced by reduced DNA fragmentation) by down-regulating NF-kB and caspase 3 activity.

CONCLUSION

For the first time, this study demonstrated that glutamine administration improved testicular I/R injury in T/D rat model by maintaining testicular redox balance, and testicular integrity and function via inhibition of I/R-induced upregulation of NF-kB signaling and caspase 3 activation.

Taurine and cardiac disease: state of the art and perspectives

Taurine is a nonessential amino acid that has received much attention. Two organs, the heart and the brain, are known to produce their own taurine, but in very limited quantities. It is for this reason that supplementation with this amino acid is necessary. Today, taurine is present in almost all energy drinks. A very vast literature reported beneficial effects of taurine in hepatic dysfunction, gastrointestinal injury, kidney diseases, diabetes, and cardiovascular diseases. Most of its effects were attributed to its modulation of Ca2+homeostasis as well as to its antioxidant properties. In this review, we will focus on the current status of taurine modulation of the cardiovascular system and discuss future avenues for its use as a supplement therapy in a specific cardiovascular disease, namely hypertrophy, and heart failure.

Preventive effects of l-glutamine on gestational fructose-induced cardiac hypertrophy: involvement of pyruvate dehydrogenase kinase-4

Gestational fructose exposure has detrimental health consequences on both the maternal and fetus or offspring in the early or later life, contributing to epidemic rise in cardiometabolic syndrome including cardiac events. l-Glutamine has been shown to mitigate cardiac metabolic stress. However, the effect of l-glutamine on cardiac hypertrophy induced by gestational fructose exposure is not known. We therefore hypothesized that l-glutamine would prevent gestational fructose-induced cardiac hypertrophy, possibly by suppression of pyruvate dehydrogenase kinase-4 (PDK-4). Pregnant Wistar rats were allotted into the control, l-glutamine, gestational fructose exposure, and gestational fructose exposure plus l-glutamine groups (6 rats in each group). The groups received distilled water (vehicle, per os), 1 g/kg body weight l-glutamine (per os), 10% fructose (w/v) and 10% fructose (w/v) plus 1 g/kg l-glutamine (per os), respectively, daily for 19 days. Data from this study showed that gestational fructose-enriched drink caused cardiac hypertrophy with correspondent body weight gain, glucose dysregulation, increased cardiac PDK-4, triglyceride, glycogen, lactate, and uric acid production. On the other hand, defective glutathione-dependent antioxidant barrier was also observed in pregnant rats taking fructose-enriched drink. However, the gestational fructose-induced cardiac hypertrophy and its correlates were attenuated by l-glutamine. The present results demonstrate that gestational fructose-enriched drink induces cardiac hypertrophy that is accompanied by increased PDK-4. The findings also suggest that the inhibitory effect of l-glutamine on PDK-4 prevents the development of cardiac hypertrophy, thereby implying that PDK-4 may be a potential novel therapeutic intervention for cardiac hypertrophy especially in pregnancy.

Metabolic alterations in a rat model of hepatic ischaemia reperfusion injury: In vivo hyperpolarized 13 C MRS and metabolic imaging

BACKGROUND & AIMS

Despite a number of studies addressing the pathophysiology of hepatic IRI, a gold standard test for early diagnosis and evaluation of IRI remains elusive. This study investigated the metabolic alterations in a rat model of hepatic IRI using the in vivo hyperpolarized ¹³C MRS and metabolic imaging.

METHODS

Hyperpolarized ¹³ C MRS with IVIM-DWI was performed on the liver of 7 sham-operated control rats and 7 rats before and after hepatic IRI.

RESULTS

The hepatic IRI-induced rats showed significantly higher ratios of [1-¹³ C] alanine/pyruvate, [1-¹³ C] alanine/tC, [1-¹³ C] lactate/pyruvate and [1-¹³ C] lactate/tC compared with both sham-operated controls and rats before IRI, whereas [1-¹³ C] pyruvate/tC ratio was decreased in IRI-induced rats. In IVIM-DWI study, apparent diffusion coefficient (ADC), f and D values in rats after hepatic IRI were significantly lower than those of rats before IRI and sham-operated controls. The levels of [1-¹³ C] alanine and [1-¹³ C] lactate were negatively correlated with ADC, f and D values, whereas the level of [1-¹³ C] pyruvate was positively correlated with these values.

CONCLUSIONS

The levels of [1-¹³ C] alanine, [1-¹³ C] lactate and [1-¹³ C] pyruvate in conjunction with IVIM-DWI will be helpful to evaluate the hepatic IRI as well as these findings can be useful in understanding the biochemical mechanism associated with hepatic damage.

Changes in the mitochondrial function and in the efficiency of energy transfer pathways during cardiomyocyte aging

The role of mitochondria in alterations that take place in the muscle cell during healthy aging is a matter of debate during recent years. Most of the studies in bioenergetics have a focus on the model of isolated mitochondria, while changes in the crosstalk between working myofibrils and mitochondria in senescent cardiomyocytes have been less studied. The aim of our research was to investigate the modifications in the highly regulated ATP production and energy transfer systems in heart cells in old rat cardiomyocytes. The results of our work demonstrated alterations in the diffusion restrictions of energy metabolites, manifested by changes in the apparent Michaelis-Menten constant of mitochondria to exogenous ADP. The creatine kinase (CK) phosphotransfer pathway efficiency declines significantly in senescence. The ability of creatine to stimulate OXPHOS as well as to increase the affinity of mitochondria for ADP is falling and the most critical decline is already in the 1-year group (middle-age model in rats). Also, a moderate decrease in the adenylate kinase phosphotransfer system was detected. The importance of glycolysis increases in senescence, while the hexokinase activity does not change during healthy aging. The main result of our study is that the decline in the heart muscle performance is not caused by the changes in the respiratory chain complexes activity but mainly by the decrease in the energy transfer efficiency, especially by the CK pathway.