Simulated Microgravity and Hypergravity Affect the Expression Level of Soluble Guanylate Cyclase, Adenylate Cyclase, and Phosphodiesterase Genesin Rat Ventricular Cardiomyocytes

Ion channels activity is regulated through soluble guanylate cyclase (sGC) and adenylate cyclase (AC) pathways, while phosphodiesterases (PDE) control the intracellular levels of cAMP and cGMP. Here we applied RNA transcriptome sequencing to study changes in the gene expression of the sGC, AC, and PDE isoforms in isolated rat ventricular cardiomyocytes under conditions of microgravity and hypergravity. Our results demonstrate that microgravity reduces the expression of sGC isoform genes, while hypergravity increases their expression. For a subset of AC isoforms, gene expression either increased or decreased under both microgravity and hypergravity conditions. The expression of genes encoding 10 PDE isoforms decreased under microgravity, but increased under hypergravity. However, under both microgravity and hypergravity, the gene expression increased for 7 PDE isoforms and decreased for 3 PDE isoforms. Overall, our findings indicate specific gravity-dependent changes in the expression of genes of isoforms associated with the studied enzymes.

Simulated Microgravity Changes the Number of Mechanically Gated and Mechanosensitive Ion Channels Genes Transcripts in Rat Ventricular Cardiomyocytes

The mechanoelectrical feedback in the heart is based on the work of mechanically gated (MGCs) and mechanosensitive (MSCs) channels. Since microgravity alters the heart's morphological and physiological properties, we hypothesized that the expression of both MGCs and MSCs would be affected. We employed RNA transcriptome sequencing to investigate changes in the gene transcript levels of MGCs and MSCs in isolated rat ventricular cardiomyocytes under control conditions and in a simulated microgravity environment. For the first time, our findings demonstrated that simulated microgravity induces alterations in the gene transcript levels of specific MGCs, such as TRPM7, TRPV2, TRPP1, TRPP2, Piezo1, TMEM63A, TMEM36B, and known MSCs, including K2P2.1, K2P3.1, Kir6.1, Kir6.2, NaV1.5, CaV1.2, KV7.1. However, other voltage-gated channels and channels lacking a voltage sensor remained unaffected. These findings suggest that the altered expression of MGCs and MSCs could lead to changes in the net currents across the membrane, ultimately impacting the heart's function.

Hypergravity Increases the Number of Gene Transcripts of Mechanically Gated and Mechanosensitive Ion Channels in Rat Ventricular Cardiomyocytes

Since hypergravity changes the morphological and physiological properties of the heart, it was assumed that the expression of ion channels that respond to cell stretching or compressing, mechanically gated channels (MGC) and mechanosensitive channels (MSC), would be affected. Using RNA transcriptome sequencing, the change in the number of transcripts for MGC and MSC genes was studied in isolated rat ventricular cardiomyocytes under 4g hypergravity for 5 days. It was shown for the first time that hypergravity induces changes in the number of transcripts of MGC genes: an increase for TRPC1, TRPC3, TRPM7, TRPP1 (PKD1), TRPP2 (PKD2), TMEM63A, TMEM63B, but a decrease for TRPV2, Piezo1, Piezo2. The number of MSC gene transcripts increases: TREK-1, Kir6.2, Nav1.5, Cav1.2, Cav1.3, Kv7.1, and Kv1.2. This potentially leads to an increase in the expression of MGC and MSC proteins leading to an increase in the net current and, as a result, pathological changes in the heart function.

[Hepatocellular damage and inflammation in various forms of alcoholic liver disease]

AIM

The aim of the study was to evaluate hepatocellular damage and immune inflammation in various forms of alcoholic liver disease (ALD).

MATERIALS AND METHODS

104 patients with ALD were examined: 15 (14.4%) with liver steatosis (LS), 19 (18.3%) with steatohepatitis and 70 (67.3%) with liver cirrhosis (LC); men 50 (48.1%), women 54 (51.9%); age 45.78.4 years. Traditional clinical, laboratory, instrumental studies were performed, the levels of fragments of cytokeratin-18 (FCK-18), cytokines IL-1, TNF-, IL-4, IL-6, IL-8 were determined by ELISA. The control group consisted of 39 healthy individuals: men 20 (51.2%), women 19 (48.7%), age 48.58.3 years.

RESULTS

In LS, an increase in the level of FCK-18 was noted with normal aminotransferase activity, the content of TNF-, IL-6, IL-1, IL-8 increased and the level of IL-4 decreased compared to those in healthy individuals. In steatohepatitis, a triple increase in aminotransferases and FCK-18 was observed compared with LS, as well as an increase in the level of inflammatory mediators, to a greater extent IL-6, to a lesser extent IL-8, TNF-, a decrease in IL-4, IL-1 remained at the same level. In LC, there was a further increase in FCK-18, significantly more pronounced than an increase in AST, and the increase in cytokines continued to the same extent, the levels of IL-6 and IL-8, to a lesser extent IL-1 and TNF-, and the level of IL-4.

CONCLUSION

With the progression of ALD from LS to steatohepatitis, hepatic cell damage was carried out by equally pronounced processes of hepatocyte necrosis and apoptosis, with the development of cirrhosis of the liver, parenchyma damage occurred mainly due to hepatocyte apoptosis. The immuno-inflammatory process progressively increased from the stage of LS to LC with IL-6 and IL-8 undergoing the greatest dynamics. FCK-18 can serve as a non-invasive marker of hepatic cell damage, and IL-6 and IL-8 markers of immune inflammation in ALD.

[DIAGNOSIS AND CLINICAL MANIFESTATIONS OF CIRRHOTIC CARDIOMYOPATHY]

The aim of the study was to determine the incidence of cirrhotic cardiomyopathy (CCMP), features of its recognition and clinical manifestations.

MATERIALS AND METHODS

The study included 102 patients with alcoholic and viral liver cirrhosis (LC) without cardiovascular history, without viremia and signs of acute alcoholic hepatitis. Echocardiography, electrocardiography (ECG) and brain natriuretic hormone (proBNP) level were investigated in all patients.

RESULTS

CCMP signs were detected in 65 (63.7%) of the 102 patients examined. All patients showed signs of electrophysiological myocardial abnormalities in ECG, signs of myocardial injury and the presence of heart failure in echocardiography, increase in proBNP. Interval QT length (0.4689 ± 0.012 s.) was significantly (p = 0.0461) higher than that of the control group. Violation of diastolic relaxation of the left ventricle was detected in 36 (55.6%) patients. The average level of proBNP was 540.85 ± 236.43 pg/ml, significantly different from the level of proBNP in healthy individuals--89.45 ± 26.43 pg/ml. The incidence of CCMP increased progressively with the severity of the Child-Pugh class and was 42.4% in patients of A class, 84.6% (p = 0.0132) in patients of B Class and 100% in patients of C class (p = 0.0219). The length of the QT interval, the proBNP level and frequency of diastolic dysfunction increased with increasing of liver cirrhosis severity.

CONCLUSION

The frequency of detection of cirrhotic cardiomyopathy was 63.7%. More pronounced CCMP signs were observed in alcoholic liver cirrhosis than in viral. The frequency of detection and severity of cirrhotic cardiomyopathy progres sively increased with the severity of liver cirrhosis. Brain natriuretic peptide was the most sensitive indicator of myocardial damage in liver cirrhosis irrespective of its etiology.