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D Acosta

Publications and source records attributed to D Acosta.

At least 181 records · Page 10Linked to original sources
PubMed1986

Cytotoxicity of ethanol in primary cultures of rat midbrain neurons.

Primary cultures of midbrain neurons were obtained from 15-day-old rat fetuses. Neuron cultures were exposed to ethanol (27 mM, 43 mM and 120 mM) for 24 h and evaluated by light microscopy, a viability measure, and protein content. Ethanol concentrations of 43 and 120 mM appeared to affect the cultures both in terms of cell viability and protein. This effect was independent of any osmotic effect, when sucrose was run as a control. We conclude that primary cultures of midbrain neurons are sensitive to relatively low concentrations of ethanol, compared to cell culture preparations used by other investigators.

Animals↗
PubMed1985

An in vitro approach to the study of target organ toxicity of drugs and chemicals.

A major goal of our laboratory has been the development of primary culture systems that retain differentiated functions and responses characteristic of intact tissues in vivo. Specifically, we have developed cellular models of primary cultures of rat heart, liver, and kidney cells to explore the mechanisms by which drugs or chemicals may be toxic to key organs of the body and to develop new techniques by which xenobiotics may be evaluated or identified as potential toxicants to living systems. The purpose of this paper is to describe our rationale and approach to the study of target organ toxicology with in vitro cellular systems.

Acetaminophen↗
PubMed1985

Ethanol toxicity in primary cultures of rat myocardial cells.

The potential cardiotoxicity of ethanol (EtOH) was evaluated in primary cultures of rat myocardial cells. EtOH cardiotoxicity was assessed in the cells on the basis of cell morphology, lactate dehydrogenase (LDH) leakage, succinate dehydrogenase (SDH) activity, and beating rates. Cells were treated with EtOH at concentrations of 600, 800, and 1000 mg% for duration of 1, 4, and 24 h and then evaluated for cardiotoxicity. Vacuole formation occurred 1 h after exposure to EtOH at 800 and 1000 mg%; by 4 h, cytosolic granular material appeared in these cells. Exposure for 24 h to all concentrations of EtOH resulted in vacuole, granule, and pseudopod formation and loss of cross-striations. Significant LDH leakage occurred at 1 h and 4 h with 800 and 1000 mg% EtOH. LDH release was significantly increased after 24 h with all concentrations. SDH activity was significantly depressed after 24 h with all concentrations of EtOH. Beating rates were altered as early as 1 h after exposure to 800 and 1000 mg% EtOH. After 24 h, those cells exposed to the highest concentrations of EtOH were not beating at all. These data suggest that primary myocardial cell cultures may be used to assess the in vitro cardiotoxicity of EtOH to the myocardial cell.

Animals↗
PubMed1985

Role of glutathione depletion in the cytotoxicity of acetaminophen in a primary culture system of rat hepatocytes.

A primary culture system of postnatal rat hepatocytes was utilized to study the cytotoxicity of acetaminophen and the toxicological significance of glutathione (GSH) depletion. The relative time of onset and magnitude of GSH depletion, lipid peroxidation and cytotoxicity were contrasted in order to gain insight into their interrelationships. Exposure of the hepatocytes to acetaminophen resulted in time- and dose-dependent depletion of cellular GSH. The acetaminophen-induced GSH depletion and ensuing lactate dehydrogenase (LDH) leakage were quite modest and delayed in onset, in contrast to that caused by iodoacetamide (IAA) and by diethylmaleate (DEM), 2 well-known depletors of GSH. There was comparable LDH leakage, irrespective of drug treatment, when GSH levels decreased to about 20% of normal. Reduction of GSH levels below the 20% threshold by IAA treatment resulted in marked LDH leakage and loss of viability. Maximal LDH leakage in response to IAA and acetaminophen preceded maximal malondialdehyde (MDA) formation, suggesting that lipid peroxidation may be a consequence of cell damage as well as GSH depletion. IAA and DEM produced a comparable, modest accumulation of MDA, yet IAA was much more cytotoxic. These findings indicate that lipid peroxidation does not play a central role in hepatocellular injury by compounds which deplete GSH, although it may contribute to degeneration of the cell. As events in the cultured postnatal hepatocytes paralleled those reported in vivo, the system can be a useful and valid model with which to study mechanisms of chemical toxicity.

Acetaminophen↗
PubMed1985

Erythromycin estolate-induced toxicity in cultured rat hepatocytes.

Primary cultures of rat hepatocytes were exposed to several concentrations of erythromycin estolate (EE). Hepatotoxicity was evaluated using lactate dehydrogenase (LDH) leakage and morphometric analysis of representative populations of cells examined optically. Results of the two techniques provided parallel information: cells exposed to the higher concentrations of EE had significantly greater LDH release and higher percentages of morphologically damaged cells. Planimetric analysis of a second set of hepatocytes showed increasing swelling of cells with increasing concentration of EE. Severe cellular swelling preceded disintegration, as hepatocytes became progressively more damaged by EE.

Animals↗
PubMed1985

Effects of cadmium and calcium on the fluidity of plasma membranes.

The fluidity of plasma membranes was assessed by steady-state fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH), a fluorescent probe. The presence of increasing concentrations of calcium (Ca) (0.5-4 mM), cadmium (Cd) (50-500 microM), or both decreased the motional freedom of the fluorescent probe molecules in plasma membranes derived from both human erythrocytes and rat hepatocytes. The effects of Cd were 3-10 times greater than those of Ca. Increasing concentrations of Cd in the presence of Ca increased the anisotropy parameter, which plateaued at lower Cd concentrations. The presence of Ca diminished the overall effects of Cd on these membranes.

Binding Sites↗
PubMed1985

Relative toxicities of several nonsteroidal antiinflammatory compounds in primary cultures of rat hepatocytes.

Primary cultures of intact, functional heptocytes were used to compare the relative toxicity of four nonsteroid antiinflammatory agents (NSAID)--benoxaprofen, orpanoxin, aspirin, and ibuprofen--with that of indomethacin. The relative toxicity of these compounds was evaluated on the basis of the release of lactate dehydrogenase, levels of urea (an indicator of a liver specific function), viability (based on dye exclusion), and morphology after a 12-h exposure to concentrations ranging from 0 to 1000 microM. Evaluation of the data obtained from these three parameters enabled us to rank these compounds from toxic to nontoxic, in decreasing order to toxicity: indomethacin greater than benoxaprofen greater than ibuprofen greater than or equal to aspirin greater than or equal to orpanoxin. Morphological evaluations of hepatocytes exposed to these agents under the same conditions supported the order of ranking for these compounds. Ultrastructurally, cells exposed to the two highest concentrations of indomethacin were severely damaged, as evidenced by marked cellular necrosis, nuclear pleomorphism, margination, swollen mitochondria, reductions in the number of microvilli, smooth endoplasmic reticulum proliferation, and cytoplasmic vacuolation. In comparison, exposure of hepatocytes to the highest dose of orpanoxin resulted only in increased vacuolation, a slight increase in cellular debris, and increased electron density of the cytoplasm of hepatocytes.

Animals↗
PubMed1985

Comparison of dantrolene sodium with erythromycin estolate using primary cultures of rat hepatocytes.

Using primary cultures of parenchymal hepatocytes as a model system, the cytotoxic potential of dantrolene sodium (DS) was compared with that of erythromycin estolate (EE)--a known hepatotoxin. Parallel morphological and functional comparisons were made, following 4-, 8-, or 24-h exposures of hepatocyte cultures, using phase contrast microscopy and lactate dehydrogenase (LDH) leakage, respectively. Four-hour exposures of cultures to rather low concentrations of EE (i.e. 50 microM) resulted in cellular necrosis and significantly elevated LDH release. As the concentration of this hepatotoxin was increased, the changes were more pronounced. However, even 4- or 8-h exposures of cultures to a maximum of 100 microM DS did not affect LDH leakage or morphological integrity, although marginally detectable morphological changes did not occur at the highest concentration after 24-h. The value of using primary parenchymal hepatocyte cultures as a model system for the assessment of xenobiotic-induced hepatotoxicity was confirmed.

Animals↗
PubMed1984

Role of calcium in isoproterenol cytotoxicity to cultured myocardial cells.

Primary cultures of rat myocardial cells were used to evaluate the cellular dynamics of calcium accumulation after exposure to isoproterenol (ISO). Non-toxic concentrations of ISO (2.4 X 10(-7) M) caused a gradual increase in myocyte calcium uptake. These effects peaked 3 min after exposure and returned to control levels within 2 min. Toxic concentrations of ISO caused a biphasic increase in calcium uptake. The initial phase peaked 1 min after exposure and returned to control levels by 3 min. A second phase was characterized by a progressive increase in calcium uptake that plateaued 10 min after exposure. Ascorbic acid (AA, 5 X 10(-3) M) and sodium bisulfite (SB, 9.6 X 10(-4) M) did not modify the calcium uptake of the initial phase, whereas propranolol (1 X 10(-6) M) and verapamil (1 X 10(-5) M) prevented the initial rise in calcium uptake. In contrast, the antioxidants prevented the the second phase of ISO-induced calcium uptake, whereas verapamil and propranolol did not. The toxic accumulation of calcium induced by ISO may be due to oxidative damage of the sarcolemma. Antioxidants may prevent the formation of oxidative metabolites from ISO and the subsequent calcium overload. Our results show that agents which modify slow calcium-channel transport do not prevent ISO-induced calcium overload in our cell culture system.

Animals↗
PubMed1984

Cadmium-induced hepatotoxicity in cultured rat hepatocytes as evaluated by morphometric analysis.

Freshly isolated hepatocytes from neonatal rats were cultured for approximately 24 h; incubated for 5, 30, or 60 min in solutions containing 0, 50, 100, or 200 microM cadmium; embedded in plastic; and sectioned for optical microscopy. The extent of cadmium-induced hepatotoxicity was evaluated by double-blind morphometric analysis (a geometricostatistical processing of two-dimensional data for the collection of three-dimensional information) whereby hepatocytes were classified on the basis of the severity of morphologic damage at the optical level. Both time and concentration effects were studied. Cultures exposed to 200 microM cadmium, for various intervals of time from 5 to 60 min, showed statistically significant reductions in the relative volume percent of normal hepatocytes, elevations (then reductions) in the relative volume percent of slightly damaged hepatocytes, increases in the relative volume percent of moderately damaged cells, and increases in the relative volume percent of severely damaged liver cells. As the concentration of cadmium was increased from 50 to 200 microM cadmium (during both 30 and 60-min exposures), significant trends were observed in cellular distribution patterns based on relative volume percent. Morphologically normal cells decreased, both slightly damaged and moderately damaged cells increased, and severely damaged cells remained unchanged. These results indicated that morphometric analysis at the optical level provided quantitative estimates for the evaluation of time- and concentration-effects of cadmium on cultured hepatocytes.

Animals↗
PubMed1984

Calcium amelioration of cadmium-induced cytotoxicity in cultured rat hepatocytes.

Parenchymal hepatocytes from neonatal rats were isolated, cultured about 24 h, exposed to cadmium with or without calcium, and processed for scanning electron microscopy. To assess the severity of cadmium-induced changes, exposed hepatocytes were categorized based upon the extent of morphological damage. Differences in surface blebbing, alterations in microvilli, variations in the degree of swelling, and changes in cell shape were used to categorize the severity of cell damage. A double-blind morphometric analysis (a geometricostatistical processing of two-dimensional data for the collection of three-dimensional information) of cellular changes was conducted for each exposure time and for each concentration of cadmium in the presence or absence of calcium. Significant decreases occurred in the percent relative volume of normal, flattened cells present in cultures exposed for 30 min to 50 or 100 microM cadmium in the absence of calcium. In contrast, the percent relative volume of severely damaged spherical cells was significantly increased after exposure to solutions containing 50 or 100 microM cadmium and lacking calcium. Percent relative volume of intermediate cells (which were slightly swollen and showed changes in microvillar number) was significantly increased following a 30 min exposure to all cadmium concentrations in the absence of calcium. The examination of hepatocytes exposed for 60 min showed that the degree of cadmium-induced cytotoxicity was more severe in the absence of calcium than was the case for the hepatocyte cultures exposed for 30 min: approximately 30% more spherical cells and 30% fewer flattened cells were present if cultures were exposed in the absence of calcium for 60 min compared to those exposed for 30 min. The degree of blebbing was significantly greater at all cadmium concentrations in the absence of calcium. The presence of calcium, therefore, reduced cadmium-induced cytotoxicity in primary cultures of rat hepatocytes subjected to morphometric analysis after scanning electron microscopy.

Animals↗
PubMed1984

Effects of cardioactive drugs on the beating activity of myocardial cell cultures isolated from offspring of trained and untrained pregnant rats.

Primary cultures of beating myocardial cells were obtained from 5-d-old offspring of trained (T) and untrained (UT), pregnant, Sprague-Dawley rats. The myocardial cells from the T and UT groups were evaluated for their beating responses to three cardioactive drugs: verapamil (V), isoproterenol (ISO), and propranolol (PRO). The myocardial cell cultures from the UT group showed complete loss of beating when the calcium (Ca++) antagonist, V, was added to the cultures for 1 h or more; the T group was able to show some beating at comparable concentrations and durations of exposure with V. The beta agonist, ISO, markedly stimulated the beating rate of both the T and UT groups, but the beating rates were higher in the UT group at comparable concentrations and durations of exposure than with the T group. When the cultures were pretreated with the beta blocker, PRO, before treatment with ISO, a concentration inhibitory effect on the beating rate was observed in both groups. However, the T cultures were more sensitive to the inhibitory effects of PRO. These results demonstrate that primary cultures of rat myocardial cells isolated from the offspring of trained and untrained pregnant rats show differential beating responses to three well-known cardioactive drugs.

Animals↗
PubMed1984

Cell injury of cultured rat myocardial cells after reoxygenation of hypoxic cultures in the presence and absence of calcium.

Primary cultures of rat myocytes were deprived of oxygen (approximately 5 mm Hg, pO2) for 2 h in the presence or absence of calcium and were subsequently incubated for different time periods under normoxic (approximately 120 mm Hg, pO2) conditions. Myocyte calcium content was determined at the end of the oxygen-free period and after repletion of oxygen. Lactate dehydrogenase (LDH) release from the cells into the medium was used as an index of cell injury. Cultures deprived of oxygen in the absence of calcium showed a significant decrease in myocyte calcium content at the end of the oxygen-free period. However, the calcium content of myocyte cultures deprived of oxygen in the presence of calcium did not change significantly. The enzyme release of both groups of oxygen-deprived cultures was similar to that of controls. A progressive increase in myocyte calcium content was observed 5, 10, 15, and 30 min after repletion of oxygen in both groups. Reoxygenation of cultures subjected to hypoxia in the presence of calcium caused minimal LDH leakage. However, major enzyme release was observed 30 min after oxygen repletion in cultures previously subjected to hypoxia in a calcium-free environment. The present study shows that reoxygenation injury is more severe in myocyte cultures previously deprived of both oxygen and calcium than in cultures deprived of oxygen in the presence of calcium.

Animals↗
PubMed1984

Attenuation by antioxidants of Na+/K+ ATPase inhibition by toxic concentrations of isoproterenol in cultured rat myocardial cells.

We have reported previously that toxic concentrations of isoproterenol caused severe alterations in the structural integrity of the sarcolemma and mitochondria found in primary cultures of rat myocardial cells [8, 9]. Mitochondrial injury was observed 1.5 h after exposure to isoproterenol, whereas leakage of intracellular ions and enzymes was observed only after prolonged exposures (greater than 4 h). Ascorbic acid and sodium bisulfite prevented the cytotoxic effects of isoproterenol in our cell culture system. Takeo et al. [13] suggested that adrenochrome (an oxidative metabolite of epinephrine) specifically inhibits the activity of the sodium/potassium ATPase. Other investigators have shown that an indole metabolite of epinephrine inhibited actomyosin ATPase [1, 4]. These inhibitory actions may result from an interaction between the oxidative metabolites and sulfhydryl groups present in the enzyme [13]. Inhibition of the sodium/potassium ATPase is associated with an increase in the intracellular concentration of Na+ and Ca2+ and a decrease in intracellular K+. Changes in the intracellular concentration of these ions are commonly seen in heart cell damage and contractile failure [2]. The present study was designed to determine if isoproterenol, a synthetic catecholamine, inhibits the sodium/potassium ATPase activity in a primary culture system of rat myocardial cells.

Animals↗
PubMed1984

Cardiotoxicity of tricyclic antidepressants in primary cultures of rat myocardial cells.

Primary cultures of myocardial cells were used to evaluate the cardiotoxic potential of various tricyclic antidepressants (TCAs). Lactate dehydrogenase (LDH) leakage, cellular viability, and beating rates were measured to compare the cardiotoxicity of amitriptyline, desipramine, imipramine, and nortriptyline. Tricyclic antidepressants were added to the cultures to give final concentrations of 1 X 10(-5), 1 X 10(-4), and 1 X 10(-3) M. Treatments lasted 1 and 4 h. All TCAs tested caused significant release of LDH and decreased cellular viability when added at 1 X 10(-3) M for 1 and 4 h. Amitriptyline was the only compound that caused significant LDH release 4 h after exposure to lower doses. Decreased viability was observed 4 h after exposure to all TCAs at a concentration of 1 X 10(-4) and 1 X 10(-3) M. Arrhythmias were observed 1 h after exposure to 1 X 10(-5) and 1 X 10(-4) M amitriptyline. All doses of amitriptyline inhibited beating 4 h after exposure. Imipramine, desipramine, and nortriptyline at a concentration of 1 X 10(-5) M decreased the beating rates of cultured myocytes 1 and 4 h after exposure. Arrhythmias and/or total inhibition of beating were observed when the cultures were exposed to higher concentrations of these compounds. Based on these data, the rank order of cardiotoxicity was amitriptyline greater than imipramine = desipramine greater than nortriptyline.

Animals↗
PubMed1983

Cytotoxicity of isoproterenol to cultured heart cells: effects of antioxidants on modifying membrane damage.

Primary cultures of rat myocytes were used to study the cardiac damage induced by toxic doses of L-isoproterenol (ISO). Cultures were exposed to varying concentrations of ISO (2.4 X 10(-5), 1 X 10(-4), and 5 X 10(-4) M) for 0.5, 1.5, 4, and 12 hr. Mitochondrial membrane fragility, myocyte potassium content (as an index of sarcolemmal damage), and cellular glutathione content were used to evaluate cellular injury. A significant increase in mitochondrial fragility was observed 0.5 hr after treatment with 5 X 10(-4) M ISO. Lower doses caused an increase in mitochondrial fragility 1.5 hr after exposure. Longer durations of ISO exposure (4 and 12 hr) were necessary to decrease cellular potassium content. Glutathione levels were minimally affected by ISO. L-Ascorbic acid (5 X 10(-3) M) or sodium bisulfite (9.6 X 10(-4) M) were added to the cultures to determine if antioxidants prevent the toxicity caused by ISO. The presence of L-ascorbic acid or sodium bisulfite in ISO-treated myocyte cultures prevented the toxic changes in mitochondrial fragility and myocyte potassium content. The data indicate that antioxidants may be useful in reducing injury induced by toxic doses of ISO. Furthermore, mitochondrial injury may be involved significantly with the development of ISO-induced cardiotoxicity.

Animals↗