ascorbic-acid and Edema--Cardiac

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) has adverse effects on the development and function of the heart in zebrafish eleutheroembryos (embryos and larvae). We previously reported that TCDD reduced blood flow in the mesencephalic vein of zebrafish eleutheroembryos long before inducing pericardial edema. In the present study, we compared early edema (pre-cardiac edema), reduction of deduced cardiac output and reduction of blood flow in the dorsal aorta and cardinal vein caused by TCDD. In the same group of eleutheroembryos, TCDD (1.0 ppb) caused pre-cardiac edema and circulation failure at the cardinal vein in the central trunk region with the similar time courses from 42 to 54 h post fertilization (hpf), while the same concentration of TCDD did not significantly affect aortic circulation in the central trunk region or cardiac output. The dependence of pre-cardiac edema on TCDD concentration (0-2.0 ppb) at 55 hpf correlated well with the dependence of blood flow through the cardinal vein on TCDD concentration. Several treatments that markedly inhibited TCDD-induced pre-cardiac edema such as knockdown of aryl hydrocarbon receptor nuclear translocator-1 (ARNT1) and treatment with ascorbic acid, an antioxidant, did not significantly prevent the reduction of cardiac output at 55 hpf caused by 2.0 ppb TCDD. TCDD caused hemorrhage and extravasation of Evans blue that was intravascularly injected with bovine serum albumin, suggesting an increase in endothelium permeability to serum protein induced by TCDD. The results suggest that the blood vessels are primary targets of TCDD in edema formation in larval zebrafish.

Topics: Animals; Antioxidants; Aryl Hydrocarbon Receptor Nuclear Translocator; Ascorbic Acid; Edema; Edema, Cardiac; Embryo, Nonmammalian; Larva; Polychlorinated Dibenzodioxins; Receptors, Aryl Hydrocarbon; Water Pollutants, Chemical; Zebrafish; Zebrafish Proteins

The cardiovascular system is one of the most characteristic and important targets for developmental toxicity by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in fish larvae. However, knowledge of the mechanism of TCDD-induced edema after heterodimerization of aryl hydrocarbon receptor type 2 (AHR2) and AHR nuclear translocator type 1 (ARNT1) is still limited. In the present study, microscopic analysis with a high-speed camera revealed that TCDD increased the size of a small cavity between the heart and body wall in early eleutheroembryos, a toxic effect that we designate as precardiac edema. A concentration-response curve for precardiac edema at 2 days post fertilization (dpf) showed close similarity to that for conventional pericardial edema at 3 dpf. Precardiac edema caused by TCDD was reduced by morpholino knockdown of AHR2 and ARNT1, as well as by an antioxidant (ascorbic acid). A selective inhibitor of cyclooxygenase type 2 (COX2), NS398, also markedly inhibited TCDD-induced precardiac edema. A thromboxane receptor (TP) antagonist, ICI-192,605 almost abolished TCDD-induced precardiac edema and this effect was canceled by U46619, a TP agonist, which was not influential in the action of TCDD by itself. Knockdown of COX2b and thromboxane A synthase 1 (TBXS), but not COX2a, strongly reduced TCDD-induced precardiac edema. Knockdown of COX2b was without effect on mesencephalic circulation failure caused by TCDD. The edema by TCDD was also inhibited by knockdown of c-mpl, a thrombopoietin receptor necessary for thromobocyte production. Finally, induction of COX2b, but not COX2a, by TCDD was seen in eleutheroembryos at 3 dpf. These results suggest a role of the COX2b-thromboxane pathway in precardiac edema formation following TCDD exposure in developing zebrafish.

Topics: Animals; Antioxidants; Aryl Hydrocarbon Receptor Nuclear Translocator; Ascorbic Acid; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Edema, Cardiac; Embryo, Nonmammalian; Gene Expression Regulation, Enzymologic; Gene Knockdown Techniques; Polychlorinated Dibenzodioxins; Receptors, Aryl Hydrocarbon; Signal Transduction; Thromboxanes; Water Pollutants, Chemical; Zebrafish; Zebrafish Proteins

Arsenic trioxide (ATO/As2O3) is a promising drug for patients with a relapse of acute promyelocytic leukemia (APL); however, it frequently causes fatal arrhythmias. This study aims to investigate the various cellular and molecular mechanisms of adverse cardiac effects and the electrophysi-ological alterations caused by As2O3. We show the dose-dependent effect of ATO (0.2, 0.4, 0.8, 1.6, 3.2, 6.4 mum) on electrically driven cardiac action potential from the papillary muscle of the guinea pig. ATO causes a significant prolongation of action potential duration (APD) at various levels of repolarization, conduction delay, and increased triangulation, which is a novel marker for the proarrhythmic potential of a compound. Electrolyte imbalance (hypomagnesemia and hypokalemia) has also been found to cause amplification of ATO toxicity. Since ion channels play a very important role in the generation of cardiac action potential, we used various ion channel modulators such as choline, minoxidil, nifedipine, and verapamil to determine whether these agents could antagonize electrophysiological alterations caused by ATO. In in vivo experiments, ATO administration to animals for 10 days caused myocardial disorganization, interstitial edema and infiltration of inflammatory cells in the heart. Efforts were also made to screen the efficacy of vitamin C against ATO toxicity. ATO also caused a significant increase in the activity of certain clinically relevant enzymes for cardiac function and antioxidant mechanismssuch as serum creatine kinase isoenzyme, lactate dehydrogenase, glutathione peroxidase and reduced glutathione. In conclusion, ATO causes significant adverse cardiac effects and we suggest that cardiac function to be monitored during treatment with ATO. Our results also indicate that the status of the body's main electrolyte content (such as magnesium and potassium) is also an influencing factor on the magnitude of toxicity of arsenic trioxide.

Topics: Action Potentials; Animals; Antineoplastic Agents; Arsenic Trioxide; Arsenicals; Ascorbic Acid; Dose-Response Relationship, Drug; Drug Antagonism; Edema, Cardiac; Guinea Pigs; Heart; Leukemia, Promyelocytic, Acute; Male; Membrane Transport Modulators; Myocardium; Oxidants; Oxides; Oxidoreductases; Vasodilator Agents

Topics: Ascorbic Acid; Bendroflumethiazide; Diuretics; Edema, Cardiac; Electrolytes; Feeding and Eating Disorders; Geriatrics; Heart Failure; Humans; Hypertension; Nausea; Potassium; Toxicology; Vitamin B Complex; Vomiting