Cultured heart cells from oyster : an experimental approach for evaluation of the toxicity of the marine pollutant tributyltin

European Community regulations on chemicals promote alternative methods to test substances presenting potential risks for the environment. In the present work, cultured atrial cells isolated from oyster (Crassostrea gigas) were used as an experimental model to investigate the toxicity of tributyltin (TBT) after short-time exposure at concentrations representative of those that can be measured in seawater, marine sediments and/or bivalves bioaccumulating this pollutant. In vitro and in vivo assays produce values of the same order of magnitude for both animal/cell survival and heart/cardiomyocyte beating rate. The survival rate of whole animals decreased from 10(-6) M TBT after 3 days. For cultured cells, the viability, evaluated using 3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide (MTT) assay, significantly decreased after two days of treatment with 10(-6) M TBT, and after six days with 10(-10) M TBT. The percentage of apoptotic cells, quantified by flow cytometry and YO-PRO (R)-1 iodide, a nucleic acid stain that only permeates cells that are beginning to undergo apoptosis, increased significantly in these cases. Moreover, intracellular concentration of Ca++ had increased after 10 min of exposition to 10(-6) M, and could be associated with apoptotic processes. As patch clamp experiments showed that Ca++ conductance was decreased, intracellular calcium increase could mainly be due to a release from internal stores. The decreases in beating rhythm could be explained by the decrease in adenosine triphosphate (ATP) production revealed by P-31 nuclear magnetic resonance (NMR) spectroscopy and confirmed by the increase of the K-ATP channel conductance. The related hyperpolarization and the disturbances of the energetic metabolism were clearly related to the loss of the atrial cell contractility and viability

Cultured heart cells from oyster : an experimental approach for evaluation of the toxicity of the marine pollutant tributyltin

European Community regulations on chemicals promote alternative methods to test substances presenting potential risks for the environment. In the present work, cultured atrial cells isolated from oyster (Crassostrea gigas) were used as an experimental model to investigate the toxicity of tributyltin (TBT) after short-time exposure at concentrations representative of those that can be measured in seawater, marine sediments and/or bivalves bioaccumulating this pollutant. In vitro and in vivo assays produce values of the same order of magnitude for both animal/cell survival and heart/cardiomyocyte beating rate. The survival rate of whole animals decreased from 10-6 M TBT after 3 days. For cultured cells, the viability, evaluated using 3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide (MTT) assay, significantly decreased after two days of treatment with 10-6 M TBT, and after six days with 10-10 M TBT. The percentage of apoptotic cells, quantified by flow cytometry and YO-PRO®-1 iodide, a nucleic acid stain that only permeates cells that are beginning to undergo apoptosis, increased significantly in these cases. Moreover, intracellular concentration of Ca++ had increased after 10 min of exposition to 10-6 M, and could be associated with apoptotic processes. As patch clamp experiments showed that Ca++ conductance was decreased, intracellular calcium increase could mainly be due to a release from internal stores. The decreases in beating rhythm could be explained by the decrease in adenosine triphosphate (ATP) production revealed by 31 P nuclear magnetic resonance (NMR) spectroscopy and confirmed by the increase of the KATP channel conductance. The related hyperpolarization and the disturbances of the energetic metabolism were clearly related to the loss of the atrial cell contractility and viability

Cardiotoxicity and myocardial infarction-associated DNA damage induced by thiamethoxam in vitro and in vivo Protective role of Trigonella foenum-graecum seed-derived polysaccharide

International audienceThe risk of pesticides on the human health and environment has drawn increasing attention. Today, new tools are developed to reduce pesticide adverse effects. This study aimed to evaluate the toxicity induced by, thiamethoxam (TMX), and the cytoprotective effect of a novel polysaccharide, named fenugreek seed water polysaccharide (FWEP) in vitro using H9c2 cardiomyoblastes and in vivo using Wistar rat model. Animals were assigned into four groups per eight rats each group 1 served as a control group, group 2 received TMX, group 3, and group 4 received both FWEP and TMX tested at two doses (100 and 200 mg/kg, respectively). Regarding the in vitro study, our results demonstrated that TMX induced a decrease in H9c2 cell viability up to 70% with the highest concentration. In vivo, TMX injection induced marked heart damage noted by a significant increase in plasma lactate dehydrogenase, creatine phosphokinase, troponin-T, aspartate amino transferase activities, cholesterol, and triglyceride levels. Concomitant alterations in cardiac antioxidant defense system revealed depletion in the levels of glutathione and non-protein thiol and an increase in the activity of superoxide dismutase, catalase, and glutathione peroxidase. Similarly, a significant increase in heart lipid, malondialdehyde, advanced oxidation protein product and in protein carbonyls levels was also noted. In addition, heart tissues histo-architecture displayed major presence of apoptosis and necrosis as confirmed by DNA degradation. However, supplementation with FWEP alleviated heart oxidative damage and genotoxicity. In this manner, ABTS radical-scavenging activity, linoleic acid oxidation tests and heart genomic and DNA nicking assay had proved FWEP strong antioxidant potential. In conclusion, FWEP provided significant protection against TMX-induced heart injury, and could be a useful and efficient agent against cardiotoxicity and atherosclerosis

Experimental work-flow diagram.

<p>PL, <i>Peroneus Longus</i>; MAP Mitogen-Activated Protein; MHC, Myosin Heavy Chain.</p

Prediction of the effects of immobilization on the force-velocity relationship.

<p>Whole muscle MHC isoform distribution in 4-wk immobilized and contralateral PL was determined from single-fibre analysis (pure and hybrid fibres), and compared to typical slow and fast muscles (Soleus and Extensor Digitorum Longus, respectively). Force-velocity curves were generated according to the Hill-type mathematical model (<i>inset</i>), by using the proportion of each MHC isoform in whole muscle. Data are expressed as mean ± SD. V, shortening velocity; V_max, maximal shortening velocity; FL, fibre length; P, isotonic tension; Po, maximal isometric tension.</p

Activation of MAP kinases in skeletal muscle during immobilization.

<p><b>A</b> Representative Western blot for phosphorylated and total ERK, p38, and JNK MAPK. <b>B</b> The MAP kinases phosphorylation in sham, 6- and 15-days immobilized PL were expressed relative to the contralateral muscle (n = 4 animals in each condition). C, contralateral; O, operated. Dashed line represents the basal levels in contralateral skeletal muscle. Error bars represent the SD. * MAPK activation significantly different from contralateral muscles (<i>P</i> < 0.05), # fold-change significantly different from sham-operated group (<i>P</i> < 0.05).</p