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

Abstract

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 14day 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.

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

“…Indeed, the expression of genes associated with cardiac contractility, such as ion channels and myofibrils, were inhibited especially in the 50 mM group, as described in the second paragraph of "Results". In addition to this, we previously reported that glycogen granules markedly increased in mouse cardiomyocytes, suggesting dysfunction in energy production, only when exposed to 50 mM ethanol for 14 days but not exposed to 12.5 mM and 200 mM ethanol 6 . As this concentration of ethanol is often detected in the blood of intoxicated humans, we speculated that this might be a boundary dose for continuance of heart contraction, occasionally resulting in "Failure of heart" (Table 5).…”

“…On the other hand, several physiological functions, "Synaptic transmission", "Stimulation of cyclic AMP" and "Sleep", (indicated in italics in Table 5) were activated only in 100 mM ethanol. Activations only in high concentrations of ethanol were also previously observed in mouse cardiomyocytes; these included increases in mitochondrial size and volume after 24-h exposure 5 and 14-day exposure 6 to 200 mM ethanol. Higher concentrations of ethanol are likely to switch cardiomyocyte functions over to certain specially activated ones 6 , because the cardiomyocytes are free from ethanol metabolism.…”

“…Cultured heart cells derived from animals, however, are free from these factors and their exposure to ethanol or its metabolites can be controlled in a preferred concentration and duration. As such, a considerable amount of research has been done pertaining to the effects of ethanol exposure for 24 or more hours on cardiac functions using cultured neonatal mouse [5][6][7][8] , neonatal rat [9][10][11][12] and adult rat 13 cardiomyocytes, as well as H9c2 cells [13][14] in efforts to obtain substantial results. Despite this, there has been no comprehensive investigation into potential alteration in heart gene expression induced by various concentrations of ethanol.…”

Cardiac Toxicity From Ethanol Exposure in Human-Induced Pluripotent Stem Cell-Derived Cardiomyocytes

“…Supplementary Table 1 shows the BAC, corresponding ethanol concentration, and signs and symptoms at that level (adapted from http://www.intox.com/tphysiology.aspx). Several animal studies reported results in response to ethanol exposure with dosages ranging from 25 to 200 mM (Danziger et al, 1991;Delbridge et al, 2000;Mashimo et al, 2003Mashimo et al, , 2015Mashimo and Ohno, 2006;Worley et al, 2015). We examined the effects of exposure of hiPSC-CMs to ethanol at the level that was at the legal limit of 17 mM and higher levels that correspond to different levels of alcohol intoxication.…”

Long term liver specific glucokinase gene defect induced diabetic cardiomyopathy by up regulating NADPH oxidase and down regulating insulin receptor and p-AMPK

“…Mitochondria are the center of fatty acid and glucose metabolism and thus are highly likely to be impacted by impaired metabolism associated with diabetes. Increased number and size of >mitochondria might be an adaptive response to hyperglycemia [39]. It has recently been shown that insulin resistance drives the cardiac mitochondrial biogenesis regulatory program via PPARα, where activation was increased due to increased fat uptake and oxidation [40,41].…”