Effect of doxorubicin and rubidazone on respiratory function and Ca2+ transport in rat heart mitochondria

doi:10.1016/0378-4274(79)90103-6

Toxicology Letters

Volume 3, Issue 1, January 1979, Pages 29-34

https://doi.org/10.1016/0378-4274(79)90103-6 Get rights and content

Abstract

The effect of 2 cardiotoxic anthracycline antibiotics on rat heart mitochondria was investigated in vitro and in vivo. Doxorubicin (D) caused marked inhibition of electron transfer reactions and of Ca²⁺ uptake into mitochondria when Ca²⁺ translocation was energized by electron transfer activities. In vitro rubidazone (R) was a potent uncoupler of oxidative phosphorylation. It inhibited Ca²⁺ translocation energized by both electron transfer activities and ATP splitting. In vivo R also caused marked uncoupling of oxidative phosphorylation, but had only a weak and transient effect on Ca²⁺ uptake when energy was provided by electron transfer activities.

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Agents Actions

(1975)

Cited by (36)

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Doxorubicin (Adriamycin^®) is a potent and broad-spectrum antineoplastic agent, the clinical utility of which is restricted by a cumulative and progressive cardiomyopathy that develops with repeated dosing. Fundamental to the cardiac failure is an interference with mitochondrial respiration and inhibition of oxidative phosphorylation. Global gene expression arrays in cardiac tissue indicate that inhibition of mitochondrial oxidative phosphorylation by doxorubicin (DOX) is accompanied by a decreased expression of genes related to aerobic fatty acid oxidation and a corresponding increase in expression of genes involved in anaerobic glycolysis, possibly as an alternate source for ATP production. The aim of this investigation was to determine whether this is also manifest at the metabonomic level as a switch in metabolic flux in cardiac tissue, and whether this can be averted by co-administering the cardioprotective drug, dexrazoxane (DZR). ¹³C-isotopomer analysis of isolated perfused hearts from male Sprague–Dawley rats receiving 6 weekly s.c. injections of 2 mg/kg DOX demonstrated a shift from the preferential oxidation of fatty acids to enhanced oxidation of glucose and lactate plus pyruvate, indicative of a compensatory shift towards increased pyruvate dehydrogenase activity. Substrate-selective isotopomer analysis combined with western blots indicate an inhibition of long-chain fatty acid oxidation and not MCAD activity or fatty acyl-carnitine transport. Co-administering DZR averted many treatment-related changes in cardiac substrate metabolism, consistent with DZR being an effective cardioprotective agent against DOX-induced cardiomyopathy. This switch in substrate metabolism resembles that described for other models of cardiac failure; accordingly, this change in metabolic flux may represent a general compensatory response of cardiac tissue to imbalances in bioenergetic demand and supply, and not a characteristic unique to DOX-induced cardiac failure itself.
Carvedilol protects against doxorubicin-induced mitochondrial cardiomyopathy
2002, Toxicology and Applied Pharmacology
Several cytopathic mechanisms have been suggested to mediate the dose-limiting cumulative and irreversible cardiomyopathy caused by doxorubicin. Recent evidence indicates that oxidative stress and mitochondrial dysfunction are key factors in the pathogenic process. The objective of this investigation was to test the hypothesis that carvedilol, a nonselective β-adrenergic receptor antagonist with potent antioxidant properties, protects against the cardiac and hepatic mitochondrial bioenergetic dysfunction associated with subchronic doxorubicin toxicity. Heart and liver mitochondria were isolated from rats treated for 7 weeks with doxorubicin (2 mg/kg sc/week), carvedilol (1 mg/kg ip/week), or the combination of the two drugs. Heart mitochondria isolated from doxorubicin-treated rats exhibited depressed rates for state 3 respiration (336 ± 26 versus 425 ± 53 natom O/min/mg protein) and a lower respiratory control ratio (RCR) (4.3 ± 0.6 versus 5.8 ± 0.4) compared with cardiac mitochondria isolated from saline-treated rats. Mitochondrial calcium-loading capacity and the activity of NADH-dehydrogenase were also suppressed in cardiac mitochondria from doxorubicin-treated rats. Doxorubicin treatment also caused a decrease in RCR for liver mitochondria (3.9 ± 0.9 versus 5.6 ± 0.7 for control rats) and inhibition of hepatic cytochrome oxidase activity. Coadministration of carvedilol decreased the extent of cellular vacuolization in cardiac myocytes and prevented the inhibitory effect of doxorubicin on mitochondrial respiration in both heart and liver. Carvedilol also prevented the decrease in mitochondrial Ca²⁺ loading capacity and the inhibition of the respiratory complexes of heart mitochondria caused by doxorubicin. Carvedilol by itself did not affect any of the parameters measured for heart or liver mitochondria. It is concluded that this protection by carvedilol against both the structural and functional cardiac tissue damage may afford significant clinical advantage in minimizing the dose-limiting mitochondrial dysfunction and cardiomyopathy that accompanies long-term doxorubicin therapy in cancer patients.
Interference with calcium-dependent mitochondrial bioenergetics in cardiac myocytes isolated from doxorubicin-treated rats
2001, Toxicology and Applied Pharmacology
In previous studies we showed that doxorubicin (DOX) interferes with mitochondrial calcium homeostasis and that cardiac mitochondria from DOX-treated rats express a dose-dependent, cumulative, and irreversible decrease in calcium-loading capacity. Associated with this is an increased sensitivity to calcium-induced cell killing of cardiac myocytes from DOX-treated rats. Because mitochondria play an important role in cytosolic calcium regulation, we questioned whether cardiac myocytes isolated from DOX-treated rats express an exaggerated response to interventions that increase cytosolic calcium. Adult male Sprague–Dawley rats received six weekly (sc) injections of either 2 mg/kg of doxorubicin or an equivalent volume of saline and were killed the following week. Cardiac myocytes were isolated and exposed in vitro to 25 μM of A23187, 20 mM of caffeine, or 500 μM of ouabain. A23187 and ouabain caused a dose-dependent increase in intracellular calcium, as measured fluorometrically with Fura-2AM. In the case of ouabain, the increase in cytosolic calcium was greater for myocytes from DOX-treated rats than for cells from control rats. With caffeine, however, the increase in intracellular calcium was not evident unless the mitochondria were depolarized. A23187 also caused depolarization of mitochondria, the extent of which was greater for cardiac myocytes from DOX-treated rats. All three agents caused depletion of cardiac myocyte ATP and cell killing, both of which were more profound in cells from DOX-treated rats than in controls. We suggest that by interfering with mitochondrial calcium regulation, long-term treatment with DOX renders myocytes susceptible to agents that increase cytosolic calcium, presumably by increasing the calcium-dependent disruption of mitochondrial function, leading to depletion of ATP and eventually cell death. This interference with mitochondrial calcium regulation may underlie the pathogenesis of DOX-induced cardiomyopathy.
Biphasic positive inotropic actions of doxorubicin in isolated guinea pig hearts: Relation to Ca<sup>2+</sup> release from the sarcoplasmic reticulum
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Doxorubicin (30 μM) caused a biphasic (early and late phase) positive inotropic effect. A high concentration (200 μM) of this agent caused a stronger early phase, but a weaker late phase. The early phase caused by the high concentration of doxorubicin was significantly reduced by cyclopiazonnic acid or thapsigargin, although it was not altered by ryanodine, verapamil, or nifedipine. The late phase in the presence of the high concentration of doxorubicin was slightly enhanced by cyclopiazonic acid, verapamil or nifedipine, and markedly enhanced by ryanodine. At the end of the 4-hr experimental period in the presence of the high concentration of doxorubicin, the positive inotropic effects of CaCl₂ were completely diminished. Verapamil almost completely restored the action of the doxorubicin.
Physiological role of the N-terminal processed P4501A1 targeted to mitochondria in erythromycin metabolism and reversal of erythromycin-mediated inhibition of mitochondrial protein synthesis
1999, Journal of Biological Chemistry
Recently, we showed that the major species of β-naphthoflavone-inducible rat liver mitochondrial P450MT2 consists of N-terminal truncated microsomal P4501A1 (+33/1A1) and that the truncated enzyme exhibits different substrate specificity as compared with intact P4501A1. The results of the present study show that P450MT2 targeted to COS cell mitochondria by transient transfection of P4501A1 cDNA is localized inside the mitochondrial inner membrane in a membrane-extrinsic orientation. Co-expression with wild type P4501A1 and adrenodoxin (Adx) cDNAs resulted in 5–7-fold higher erythromycin N-demethylation (ERND) in the mitochondrial fraction but minimal changes in the microsomal fraction of transfected cells. Erythromycin, a potent inhibitor of bacterial and mitochondrial protein synthesis, caused 8–12-fold higher accumulation of CYP1A1 mRNA, preferential accumulation of P450MT2, and 5–6-fold higher ERND activity in the mitochondrial compartment of rat C6 glioma cells. Consistent with the increased mitochondrial ERND activity, co-expression with P4501A1 and Adx in COS cells rendered complete protection against erythromycin-mediated mitochondrial translation inhibition. Mutations that specifically affect the mitochondrial targeting of P4501A1 also abolished protection against mitochondrial translation inhibition. These results for the first time suggest a physiological function for the xenobiotic inducible cytochrome P4501A1 against drug-mediated mitochondrial toxicity.
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1996, Toxicology
Cytotoxic mechanisms of the antitumor agents daunorubicin and doxorubicin were elucidated in isolated cardiomyocytes from adult rats. Incubation with daunorubicin resulted in a concentration-dependent loss of cell viability and changes of the cell structure. Only the highest concentration of doxorubicin (1 mM) caused similar effects. Doxorubicin was found to stimulate oxygen consumption by cardiomyocytes (about 20%), while the opposite effect was observed after daunorubicin treatment. A rapid decrease of the mitochondrial ATP content (more than 40%) and elevation of the cytosolic ADP level (doxorubicin 2-fold and daunorubicin 6-fold) was followed by increased release of adenosine and inosine to the surrounding medium. When myocytes were exposed to an anthracycline concentration lower than plasma levels measured clinically (0.15 μM), doxorubicin and daunorubicin significantly decreased the intracellular ADP and NAD levels. Isolated cardiomyocytes were found to be able to form daunorubicinol from daunorubicin. In contrast, no conversion of doxorubicin was detected in our experiments. In conclusion, our data demonstrate that decreased ATP production and increased nucleoside formation are major events in the toxicity induced by daunorubicin and doxorubicin in isolated cardiomyocytes. The results also suggest that the toxic effects may be caused by separate mechanisms.

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Effect of doxorubicin and rubidazone on respiratory function and Ca2+ transport in rat heart mitochondria

Abstract

Lancet

J. Mol. Cell. Cardiol.

J. Biol. Chem.

J. Mol. Cell. Cardiol.

Biochem. Med.

Cardiac toxicity of Adriamycin-DNA complex and Rubidazone: evaluation by electrocardiogram and endomyocardial biopsy

Cancer Treatment Rep.

An anthracycline antibiotic-induced cardiomyopathy in rabbits

Lab. Invest.

Overview of cardiac pathology in relation to anthracycline cardiotoxicity

Cancer Treatment Rep.

Model system for cardiotoxic effects of anthracyclines

Antibiot. Chemother.

Anthracycline cardiomyopathy monitored by morphologic changes

Cancer Treatment Rep.

Effects of seven anthracycline antibiotics on electrocardiogram and mitochondrial function of rat heart

Agents Actions

Effect of doxorubicin and rubidazone on respiratory function and Ca²⁺ transport in rat heart mitochondria