Effect of Ethanol on Gene Expression in Beating Neonatal Rat Cardiomyocytes: Further Research with Ingenuity Pathway Analysis Software.

BACKGROUND: There have been no comprehensive studies of changes in heart gene expression due to ethanol exposure. Therefore, we attempted to determine gene expression in cultured neonatal rat cardiomyocytes exposed to ethanol (0, 10, 50, 100 mM) for 24 h. METHODS: The total RNA extract of beating cardiomyocytes was evaluated by DNA microarray analysis, and fold changes (FCs) in differential gene expression of ethanol-exposed cardiomyocytes were analyzed against the control using Ingenuity Pathway Analysis (IPA) software. RESULTS: The 1,394 genes with an |FC| of ≥1.8 were uploaded to IPA. IPA predicted 23 canonical pathways working in the ethanol groups. Three canonical pathways related to ethanol degradation- "Ethanol Degradation IV", "Oxidative Ethanol Degradation III", and "Ethanol Degradation II" -were inhibited in the ethanol groups. IPA predicted "ethanol" as an upregulated upstream regulator of the network with 22 downstream members for the 100 mM ethanol group only. Three members (NTRK2, TGFB3, and TLR8) were activated in all groups. Certain cellular functions were predicted to be changed dose-dependently. "Myocarditis" was dose-dependently inhibited, whereas "Cell death of heart cells" was dose-dependently activated. Several functions were inhibited in 50 mM ethanol only, eg, "Failure of heart" was enhanced in 50 mM ethanol only. Certain functions were activated in 100 mM ethanol only. "Cardiac fibrosis" was not predicted in any ethanol group. CONCLUSIONS: IPA predicted that ethanol-induced activation or inhibition of canonical pathways and functions of cardiomyocyte depended on ethanol concentration, and 3 networks related to heart functions for cardiomyocytes exposed to 3 concentrations of ethanol.

Cultured Neonatal Rat Cardiomyocytes Continue Beating Through Upregulation of CTGF Gene Expression.

BACKGROUND: Some cultured neonatal rat cardiomyocytes continue spontaneous beating even in serum-free medium. The present study explored the cause and genes responsible for this phenomenon. METHODS: Ingenuity Pathway Analysis (IPA) software was used to analyze fold changes in gene expression in beating neonatal rat cardiomyocytes, as compared with non-beating cardiomyocytes, which were obtained from DNA microarray data of total RNA extracts of cardiomyocytes. To confirm the involvement of the 8 genes selected by IPA prediction, cellular protein abundances were determined by Western blot. The gene expression of connective tissue growth factor (CTGF) was substantially higher in beating cardiomyocytes than in non-beating cardiomyocytes; thus, CTGF protein content released from cardiomyocytes into the culture medium was examined. RESULTS: IPA showed that the "Apelin Cardiac Fibroblast Signaling Pathway" was significantly inhibited and that microtubule dynamics and cytoskeleton organization were significantly activated. Each fluctuation in the cellular abundances of the 8 proteins in beating cardiomyocytes, as compared with non-beating cardiomyocytes, was primarily in the same direction as that of gene expression. However, the cellular CTGF protein abundance as well as CTGF content released into the medium did not substantially differ between beating and non-beating cardiomyocytes. CONCLUSIONS: The present results suggest that the large increase in CTGF gene expression in beating cardiomyocytes is not a cause but a result of beating, which may provide a putative pathway for controlling beating. Beating is sustained by developed cardiomyofibrils and directly upregulates CTGF gene expression, which is not followed by CTGF protein synthesis.

Ethanol Dose- and Time-dependently Increases α and ß Subunits of Mitochondrial ATP Synthase of Cultured Neonatal Rat Cardiomyocytes.

Mitochondria are target subcellular organelles of ethanol. In this study, the effects of ethanol on protein composition was examined with 2-dimensional electrophoresis of protein extracts from cultured neonatal rat cardiomyocytes exposed to 100 mM ethanol for 24 hours. A putative ß subunit of mitochondrial ATP synthase was increased, which was confirmed by Western blot. The cellular protein abundances in the α and ß subunits of ATP synthase increased in dose (0, 10, 50, and 100 mM) - and time (0.5 hour and 24 hours) -dependent manners. The DNA microarray analysis of total RNA extract demonstrated that gene expression of the corresponding messenger RNAs of these subunit proteins did not significantly alter due to 24-hour ethanol exposure. Therefore, protein expression of these nuclear-encoded mitochondrial proteins may be regulated at the translational, rather than the transcriptional, level. Alternatively, degradation of these subunit proteins might be decreased. Additionally, cellular ATP content of cardiomyocytes scarcely decreased following 24-hour exposure to any examined concentrations of ethanol. Previous studies, together with this study, have demonstrated that protein abundance of the α subunit or ß subunit or both subunits of ATP synthase after ethanol exposure or dysfunctional conditions might differ according to tissue: significant increases in heart but decreases in liver and brain. Thus, it is suggested that the abundance of subunit proteins of mitochondrial ATP synthase in the ethanol-exposed heart, being different from that in the liver and brain, should increase dose-dependently through either translational upregulation or decreased degradation or both to maintain ATP production, as the heart requires much more energy than other tissues for continuing sustained contractions.

Dose-Dependent Change in Elimination Kinetics of Ethanol due to Shift of Dominant Metabolizing Enzyme from ADH 1 (Class I) to ADH 3 (Class III) in Mouse.

ADH 1 and ADH 3 are major two ADH isozymes in the liver, which participate in systemic alcohol metabolism, mainly distributing in parenchymal and in sinusoidal endothelial cells of the liver, respectively. We investigated how these two ADHs contribute to the elimination kinetics of blood ethanol by administering ethanol to mice at various doses, and by measuring liver ADH activity and liver contents of both ADHs. The normalized AUC (AUC/dose) showed a concave increase with an increase in ethanol dose, inversely correlating with ß. CL(T) (dose/AUC) linearly correlated with liver ADH activity and also with both the ADH-1 and -3 contents (mg/kg B.W.). When ADH-1 activity was calculated by multiplying ADH-1 content by its V(max⁡)/mg (4.0) and normalized by the ratio of liver ADH activity of each ethanol dose to that of the control, the theoretical ADH-1 activity decreased dose-dependently, correlating with ß. On the other hand, the theoretical ADH-3 activity, which was calculated by subtracting ADH-1 activity from liver ADH activity and normalized, increased dose-dependently, correlating with the normalized AUC. These results suggested that the elimination kinetics of blood ethanol in mice was dose-dependently changed, accompanied by a shift of the dominant metabolizing enzyme from ADH 1 to ADH 3.

Ethanol decreases cellular protein content and mitochondrial membrane potential of cultured neonatal rat cardiomyocytes: microassays with fluorometric and spectrometric plate readers.

BACKGROUND: Ethanol decreases protein synthesis and mitochondrial respiration of the heart. We developed a new time-saving, non-radioactive, small-scale method to determine ethanol-induced alteration in cellular protein content of the cells cultivated in a 96-well plate. To verify the utility of our small-scale method, we used endothelin-1 (ET-1) as a positive control. METHODS: Neonatal rat cardiomyocytes were cultivated in a 96-well plate and exposed to ethanol (10, 50 and 100 mM) or ET-1 (100 nM). The protein content per cell was determined by measuring both the DNA (Hoechst 33258) and protein amounts of the same well with fluorometric and spectrometric plate readers. We also examined ultrastructure, mitochondrial membrane potential (deltapsim) using JC-1 (5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolylcarbocyanine iodide), anaerobic glycolysis measured by lactate amount released to the medium, and superoxide production using dihydroethidium. RESULTS: As expected, ethanol dose- and time-dependently decreased protein content per cell of cardiomyocytes at 24 and 48 h, while ET-1 time-dependently increased it. Ultrastructurally, ethanol decreased rough endoplasmic reticulum at 24 h, whereas ET-1 increased it as well as Golgi apparatus. Among ethanol groups, only 100 mM ethanol affected deltapsim: hyperpolarization just after exposure but slight depolarization at 24 h. ET-1 significantly depolarized deltapsim at 24 h, but the depolarization was within the physiological fluctuation. Ethanol did not change the lactate release at 3 and 24 h. Ethanol did not increase superoxide production at 24 h, but rather 10 mM ethanol significantly decreased it. CONCLUSION: Our small-scale method was able to demonstrate that ethanol and ET-1 induced expected alterations in protein content per cell with dose- and time-dependencies and statistically significant differences compared with the control, thereby validating the practical use of this method. Ultrastructural alterations supported the biochemical results. The ethanol-decreased cellular protein content might partly result from energy shortage attributable to reduced mitochondrial respiration, which was not compensated by anaerobic glycolysis.

Maturation of whisky changes ethanol elimination kinetics and neural effects by increasing nonvolatile congeners.

BACKGROUND: The maturation of distilled spirits is known to change constituent congeners to improve the qualities of smell and taste. However, it has been largely unknown how maturation modifies the pharmacokinetics or neuropharmacological effects of ethanol. We used single malt whiskies to investigate the effects of spirit maturation on ethanol metabolism and drunkenness. METHODS: Mice were injected with 5-year (5-y) or 20-year (20-y) aged single malt whisky with a concentration of 20% (w/v) ethanol at a dose of 3 g/kg. The concentrations of ethanol and its metabolites in the blood and the duration of loss of righting reflex (LORR) were compared between the 2 whisky groups. In addition, the effects of nonvolatile congeners in whisky on the biomedical reactivities of ethanol were investigated by administering a nonvolatile fraction added to a 20% ethanol solution, whose fraction was prepared by evaporating 16-y whisky. Liver alcohol dehydrogenase (ADH) activity was measured with whisky as the substrate or in the presence of nonvolatile congeners with ethanol as the substrate. RESULTS: The rate of ethanol elimination (mmol/kg/h) was smaller in the 20-y whisky group than in the 5-y group (p<0.01 by Fisher's protected least significant difference), which resulted in lower concentrations of blood acetaldehyde and acetate in the former group than in the latter group (p<0.01 by ANOVA). Nonvolatile congeners added to the ethanol solution also depressed the rate of ethanol elimination in mice. In vitro studies demonstrated that liver ADH activity measured with whisky as the substrate was decreased as a function of the age of the whisky, and that the activity measured with ethanol as the substrate was strongly inhibited by nonvolatile congeners. The duration of LORR was longer in the 20-y group than in the 5-y group (p<0.01). Nonvolatile congeners also prolonged the duration of ethanol-induced LORR, when administered together with ethanol. CONCLUSION: Maturation of whisky delayed ethanol metabolism to lower the level of blood acetaldehyde and acetate with increasing inhibition of liver ADH activity by nonvolatile congeners. It also prolonged drunkenness by enhancing the neurodepressive effects of ethanol, due to increases in the amount of nonvolatile congeners. These biomedical effects of whisky maturation may reduce aversive reactions and cytotoxicity due to acetaldehyde, and may also limit overdrinking with the larger neurodepression.

Ethanol hyperpolarizes mitochondrial membrane potential and increases mitochondrial fraction in cultured mouse myocardial cells.

Cultured mouse heart-derived myocardial and non-muscle cells were exposed to ethanol, stained with cell-permeant fluorescent vital probes, JC-1 (5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolyl-carbocyanine iodide) and oxidation-sensitive dihydrorhodamine 123, and analyzed by flow cytometry to elucidate ethanol-induced time-wise alterations in the mitochondrial membrane potential (DeltaPsim) and the production of reactive oxygen species (ROS). Ethanol (50 and 200 mM) not only hyperpolarized DeltaPsim of both types of cells but also dose-dependently increased ROS production at 24 h, although a 200-mM dose reduced the production until 3 h. These cell pathophysiological reactions suggest the depression of mitochondrial ATPase and mitochondrial respiratory chain. However, differences between these cells appeared after a 24-h exposure to 200 mM ethanol: the increase in ROS production was approximately twice as large for myocardial cells as for non-muscle cells; and the side-scatter parameter of light scattering significantly increased for myocardial cells, but not for non-muscle cells. All these myocyte-specific alterations indicate an increase in the mitochondrial fraction in a cell. This reaction might be a countermeasure against ethanol-induced dysfunction of mitochondrial respiration that is needed to meet the energy requirements of spontaneous myocardial contractions.

Chronic effects of ethanol on cultured myocardial cells: ultrastructural and morphometric studies.

Ultrastructural alterations of the myocardium due to chronic ethanol exposure were investigated using an in vitro system-mouse ventricular myocardial cells in a monolayer culture, which were spontaneously and synchronously contracting-by chronic exposure to 12.5, 50, and 200 mM ethanol for up to 21 days. Morphometric analyses revealed that exposure to 12.5 mM ethanol for 14 days induced an increase in the number of residual bodies, which are lysosomes containing electron-dense, amorphous materials. Some cells exposed to 50 mM ethanol for 14 days contained an accumulation of glycogen granules, increasing in inverse proportion to the mitochondrial volume. The volumetric proportion of myofibrils on day 14 decreased as the ethanol dose became lower, and was in proportion to large and giant mitochondria within the limits of three ethanol groups. Dose-dependent increases in the size and volumetric proportion of mitochondria were observed after the 14-day exposure; at a low dose (12.5 mM) mitochondria of usual size tended to increase, whereas at a high dose (200 mM) giant mitochondria increased. Coincidentally with this mitochondrial increase or gigantism, all ethanol groups showed higher beat rates than the control. Consequently, it is most likely that chronic 14-day exposures to these three ethanol doses remodel the cellular function of the in vitro myocardium in different ways; the 200-mM dose induced mitochondrial hypertrophy, an adaptive response to switch myocardial energy metabolism over to some special one; the 50-mM dose was a boundary dose; and the 12.5-mM dose mostly mimicked the chronic in vivo administration of ethanol and induced slightly degenerative alterations-increased residual bodies and lysosomes, decreased myofibrils and lowered mitochondrial respiratory function.