Effect of ethanol on function of the rat heart and skeletal muscles

Robert's Intragastric Alcohol-Induced Gastric Lesion Model as an Escalated General Peripheral and Central Syndrome, Counteracted by the Stable Gastric Pentadecapeptide BPC 157

We redefined Robert’s prototypical cytoprotection model, namely the intragastric administration of 96% alcohol in order to generate a general peripheral and central syndrome similar to that which occurs when major central or peripheral veins are occluded in animal models. With this redefinition, we used Robert’s model to examine the cytoprotective effects of the stable gastric pentadecapeptide BPC 157. The intragastric administration of alcohol induced gastric lesions, intracranial (superior sagittal sinus) hypertension, severe brain swelling and lesions, portal and vena caval hypertension, aortal hypotension, severe thrombosis, inferior vena cava and superior mesenteric vein congestion, azygos vein failure (as a failed collateral pathway), electrocardiogram disturbances, and heart, lung, liver and kidney lesions. The use of BPC 157 therapy (10 µg/kg or 10 ng/kg given intraperitoneally 1 min after alcohol) counteracted these deficits rapidly. Specifically, BPC 157 reversed brain swelling and superior mesenteric vein and inferior vena caval congestion, and helped the azygos vein to recover, which improved the collateral blood flow pathway. Microscopically, BPC 157 counteracted brain (i.e., intracerebral hemorrhage with degenerative changes of cerebral and cerebellar neurons), heart (acute subendocardial infarct), lung (parenchymal hemorrhage), liver (congestion), kidney (congestion) and gastrointestinal (epithelium loss, hemorrhagic gastritis) lesions. In addition, this may have taken place along with the activation of specific molecular pathways. In conclusion, these findings clarify and extend the theory of cytoprotection, offer an approach to its practical application, and establish BPC 157 as a prospective cytoprotective treatment.

Comparison of Toxicity of Taurine and GABA in Combination with Alcohol in 7-Day-Old Mice

Previously, we described the combined toxicity of taurine and alcohol, and assumed hypoglycemia to be one reason of this toxicity. To understand whether taurine-ethanol combined toxicity is exclusively connected to taurine or whether other inhibitory amino acids may have similar effects when combined with ethanol, we tested different doses of gamma-aminobutyric acid (GABA) in combination with ethanol in 7-day-old mice. The minimal dose of GABA in combination with 5 g/kg ethanol which could kill a mouse was 2 g/kg. GABA combined with ethanol at doses of 3 g/kg, 4 g/kg, 6 g/kg induced lethality of 30%, 90% and 100%, correspondingly. Taurine at the doses of 4 and 6 g/kg combined with ethanol induced death in 60 and 100% of mice. Ethanol (5 g/kg), taurine (6 g/kg), GABA (4 g/kg) administered alone and the combination of ethanol (5 g/kg) with taurine (3 g/kg) have no lethal effects. GABA (6 g/kg) applied alone induced 90% lethality. Taurine or GABA alone decreased blood glucose in a dose-depending manner. Ethanol potentiated GABA- and taurine-induced decrease in blood glucose and in some animals it dropped from 8.8 (intact) to a hypoglycemic level 3.1-3.3 mmol/L (GABA 4 g/kg, taurine 6 g/kg), but this may not be considered a single reason of death. We conclude that the combination of GABA and ethanol has a lethal effect and this is stronger than the combined toxicity of ethanol and taurine.

A low dose of alcohol does not impact skeletal muscle performance after exercise-induced muscle damage

Moderate, acute alcohol consumption after eccentric exercise has been shown to magnify the muscular weakness that is typically associated with exercise-induced muscle damage (EIMD). As it is not known whether this effect is dose-dependent, the aim of this study was to investigate the effect of a low dose of alcohol on EIMD-related losses in muscular performance. Ten healthy males performed 300 maximal eccentric contractions of the quadriceps muscles of one leg on an isokinetic dynamometer. They then consumed either a beverage containing 0.5 g of alcohol per kg bodyweight (as vodka and orange juice) or an isocaloric, isovolumetric non-alcoholic beverage. At least 2 weeks later, they performed an equivalent bout of eccentric exercise on the contralateral leg after which they consumed the other beverage. Measurement of peak and average peak isokinetic (concentric and eccentric) and isometric torque produced by the quadriceps was made before and 36 and 60 h post-exercise. Significant decreases in all measures of muscular performance were observed over time under both conditions (all P < 0.05); however, no difference between treatments was evident at any of the measured time points (all P > 0.05). Therefore, consumption of a low dose of alcohol after damaging exercise appears to have no effect on the loss of force associated with strenuous eccentric exercise.

Laboratory models available to study alcohol-induced organ damage and immune variations: choosing the appropriate model

The morbidity and mortality resulting from alcohol-related diseases globally impose a substantive cost to society. To minimize the financial burden on society and improve the quality of life for individuals suffering from the ill effects of alcohol abuse, substantial research in the alcohol field is focused on understanding the mechanisms by which alcohol-related diseases develop and progress. Since ethical concerns and inherent difficulties limit the amount of alcohol abuse research that can be performed in humans, most studies are performed in laboratory animals. This article summarizes the various laboratory models of alcohol abuse that are currently available and are used to study the mechanisms by which alcohol abuse induces organ damage and immune defects. The strengths and weaknesses of each of the models are discussed. Integrated into the review are the presentations that were made in the symposium "Methods of Ethanol Application in Alcohol Model-How Long is Long Enough" at the joint 2008 Research Society on Alcoholism (RSA) and International Society for Biomedical Research on Alcoholism (ISBRA) meeting, Washington, DC, emphasizing the importance not only of selecting the most appropriate laboratory alcohol model to address the specific goals of a project but also of ensuring that the findings can be extrapolated to alcohol-induced diseases in humans.

Acetaldehyde alters Ca2+-release channel gating and muscle contraction in a dose-dependent manner

We studied whether acetaldehyde, which is produced by alcohol consumption, impacts ryanodine receptor (RyR) activity and muscle force. Exposure to approximately 50-200 microM acetaldehyde enhanced channel activity of frog RyR and rabbit RyR1 incorporated into lipid bilayers. An increase in acetaldehyde to 1 mM modified channel activity in a time-dependent manner, with a brief activation and then inhibition. Application of 200 microM acetaldehyde to frog fibers increased twitch tension. The maximum rate of rise of tetanus tension was accelerated to 1.5 and 1.74 times the control rate on exposure of fibers to 50 and 200 microM acetaldehyde, respectively. Fluorescence monitoring with fluo 3 demonstrated that 200-400 microM acetaldehyde induced Ca(2+) release from the sarcoplasmic reticulum (SR) in frog muscles. Acetaldehyde at 1 mM inhibited twitch tension by approximately 12%, with an increased relaxation time after a small, transient twitch potentiation. These results suggest that moderate concentrations of acetaldehyde can elicit Ca(2+) release from the SR by increasing the open probability of the RyR channel, resulting in increased tension. However, the effects of acetaldehyde at clinical doses (1-30 microM) are unlikely to mediate alcohol-induced acute muscle dysfunction.

Protein and mRNA levels of the myosin heavy chain isoforms Ibeta, IIa, IIx and IIb in type I and type II fibre-predominant rat skeletal muscles in response to chronic alcohol feeding

Alcoholic myopathy occurs in between one and two-thirds of all alcohol misusers and is thus one of the most prevalent muscle disorders (2000 cases per 100,000 population). It is characterised by myalgia, muscle weakness and loss of lean tissue mass. Histological features include a reduction in the diameter of Type II muscle fibres, particularly the IIb fibre subset. In contrast, Type I fibres are relatively protected. It is possible that the myopathy is due to perturbations in myosin protein and mRNA expression. To test this hypothesis, we fed rats a liquid diet containing 35% of calories as ethanol. Control rats were pair-fed identical amounts of the same diet in which ethanol was replaced by isocaloric glucose. At the end of 6 weeks, total myofibrillary proteins and myosin heavy chain (MyoHC) Ibeta, IIa, IIx and IIb protein and mRNA were analysed in the plantaris (Type II fibre-predominant) and soleus (Type I fibre-predominant) muscles. The data showed that there were significant reductions in the total myofibrillary protein content in the plantaris of ethanol fed rats compared to pair-fed controls (P < 0.05). These changes in the plantaris were accompanied by reductions in total myosin (P < 0.025), as a consequence of specific reductions in the Ibeta, (P < 0.01), IIx (P < 0.05) and IIb (P < 0.05) protein isoforms. The mRNA levels of Ibeta were significantly reduced in the plantaris (P < 0.05). However, mRNA levels of IIa, IIx and IIb in the plantaris were not significantly affected by alcohol feeding. Other changes in the plantaris included significant reductions in desmin (P < 0.01), actin (P < 0.025), and troponin-I (P < 0.05) compared to pair-fed controls. In the soleus, the only significant changes related to a fall in Ibeta mRNA levels and a decline in troponin-C content. We conclude that in the rat, alcoholic myopathy is a feature of Type II fibre rich muscles and is accompanied by multiple protein changes. The decline in specific myosin protein levels, such as IIx and IIb in the absence of corresponding reductions in their mRNAs, is probably due to altered proteolysis or more likely reductions in translational efficiencies, rather than changes in transcription.

Direct inhibition of voltage-dependent Ca(2+) fluxes by ethanol and higher alcohols in rabbit T-tubule membranes

The effects of ethanol and higher alcohols on 45Ca(2+) fluxes, mediated by voltage-dependent Ca(2+) channels (VDCCs), were investigated in inside-out transverse (T)-tubule membrane vesicles from rabbit skeletal muscle. 45Ca(2+) effluxes were induced by membrane potentials generated via establishing K(+) gradients across the vesicles, and were significantly inhibited by the inorganic Ca(2+) channel blocker La(3+) (1 mM) and the Ca(2+) channel antagonist nifedipine (1-10 microM). Ethanol, in the concentration range of 100-400 mM, caused a significant suppression of depolarization-induced 45Ca(2+) fluxes. Ethanol also functionally modulated the effect of nifedipine (1-10 microM) and the Ca(2+) channel agonist Bay K 8644 (1 microM) on Ca(2+) effluxes. Pretreatment with pertussis toxin (5 microg/ml) or phorbol 12-myrstate 13-acetate (PMA, 50 nM) did not affect the ethanol inhibition of 45Ca(2+) fluxes. Further experiments with alcohols revealed that butanol, hexanol, octanol and decanol also significantly inhibited 45Ca(2+) effluxes. However, undecanol and dodecanol did not cause any significant change on 45Ca(2+) fluxes, indicating that the effects of alcohols on 45Ca(2+) effluxes exhibit a cut-off phenomenon. In radioligand binding studies, it was found that at the concentrations used in flux studies, alcohols did not alter the characteristics of the specific binding of [3H]PN 200-110 to T-tubule membranes. Results indicate that ethanol directly inhibits the function of voltage-dependent Ca(2+) channels without modulating the specific binding of Ca(2+) channel ligands of the dihydropyridine class, and that this inhibition is independent of intracellular Ca(2+) levels.

H(2)O(2) and ethanol act synergistically to gate ryanodine receptor/calcium-release channel

We examined the effect of low concentrations of H(2)O(2) on the Ca(2+)-release channel/ryanodine receptor (RyR) to determine if H(2)O(2) plays a physiological role in skeletal muscle function. Sarcoplasmic reticulum vesicles from frog skeletal muscle and type 1 RyRs (RyR1) purified from rabbit skeletal muscle were incorporated into lipid bilayers. Channel activity of the frog RyR was not affected by application of 4.4 mM (0.02%) ethanol. Open probability (P(o)) of such ethanol-treated RyR channels was markedly increased on subsequent addition of 10 microM H(2)O(2). Increase of H(2)O(2) to 100 microM caused a further increase in channel activity. Application of 4.4 mM ethanol to 10 microM H(2)O(2)-treated RyRs activated channel activity. Exposure to 10 or 100 microM H(2)O(2) alone, however, failed to increase P(o). Synergistic action of ethanol and H(2)O(2) was also observed on the purified RyR1 channel, which was free from FK506 binding protein (FKBP12). H(2)O(2) at 100-500 microM had no effect on purified channel activity. Application of FKBP12 to the purified RyR1 drastically decreased channel activity but did not alter the effects of ethanol and H(2)O(2). These results suggest that H(2)O(2) may play a pathophysiological, but probably not a physiological, role by directly acting on skeletal muscle RyRs in the presence of ethanol.

Ethanol acutely decreases calcium transients in cultured human myotubes

Ethanol consumption frequently leads to a number of skeletal muscle disorders, including acute and chronic alcoholic myopathy. Ethanol has been found to interfere with signal transduction mechanisms in cardiac and smooth muscle cells. We studied the effects of ethanol on the intracellular calcium ([Ca2+]i) transients responsible for excitation-contraction coupling in human myotubes from chronic alcoholic patients and healthy controls. Cultured myotubes were loaded with the fluorescent Ca2+ indicator fura-2 and evaluated on a single-cell basis. Following electrical stimulation, ethanol caused a significant reversible dose-dependent reduction in [Ca2+]i transient amplitude, achieving a mean decrease of 36+/-5% at 300 mM ethanol (p < 0.01), without modifying the basal [Ca2+]i. This acute effect of ethanol was similar in myotubes obtained from chronic alcoholics and controls. Similarly, ethanol caused a dose-dependent reduction of [Ca2+]i transient amplitude in control samples when depolarization was elicited by 100 mM KCl (p < 0.01). Several potential mechanisms of ethanol action were studied in control muscle samples. Sarcolemmal Ca2+ entry was measured indirectly by monitoring Mn2+-quenching of intracellular fura-2 via the nitrendipine-sensitive Ca2+ channels during electrical pacing. Ethanol at doses of 100 mM and greater caused a dose-dependent reduction in the rate of quench (p < 0.01). In addition, the intracellular pool of Ca2+ releasable by caffeine was found to be reduced at 300 mM ethanol (p < 0.05). We conclude that ethanol reduces the [Ca2+]i transients underlying excitation-contraction coupling in human myotubes, and that this occurs to a similar extent in cells obtained from chronic alcoholics and controls. This acute effect of ethanol was primarily due to an inhibitory effect of ethanol on sarcolemmal Ca2+ influx via voltage-operated Ca2+ channels, although there may also be an effect on the Ca2+ sarcoplasmic reticulum loading state.