Antimuscarinic action of doxorubicin does not involve free-radical formation in isolated guinea pig hearts.
It has been proposed that the cardiotoxicity of anthracycline anticancer drugs involves free-radical formation. One early manifestation of toxicity appears to be caused by the antimuscarinic actions of these drugs. Accordingly, we examined whether the antimuscarinic action of one of these drugs, doxorubicin, is altered by antioxidants. In electrically stimulated left atrial muscle preparations obtained from guinea pig hearts, doxorubicin significantly increased the tissue concentration of thiobarbituric acid-reactive substance indicating increased lipid peroxidation. This effect of doxorubicin was significantly suppressed by the antioxidants alpha-tocopherol, dexrazoxane, and epigallocatechin gallate. Carbachol produced a concentration-dependent negative inotropic effect in our atrial preparations. Doxorubicin caused a seemingly parallel rightward shift of the concentration-response curve for carbachol. Neither alpha-tocopherol, dexrazoxane, nor epigallocatechin gallate reversed this effect of doxorubicin. The results indicate that in extirpated heart tissue, doxorubicin causes lipid peroxidation through the formation of free radicals. However, this effect of doxorubicin is unrelated to its antimuscarinic action.
Laboratory of Toxicology, School of Veterinary Medicine, Kitasato University, 35-1 Higashi 23-bancho, Towada-shi, Aomori 034-8628, Japan.
Takushi
T
Sasaki
Shunji
S
Ueno
Yukio
Y
Hara
Tsuyoshi
T
Uchide
Kyosuke
K
Temma
D000818:Animals; D004305:Dose-Response Relationship, Drug; D004317:Doxorubicin / Q000494:pharmacology*; D005609:Free Radicals / Q000378:metabolism*; D006168:Guinea Pigs; D006321:Heart / Q000187:drug effects* / Q000502:physiology*; D008297:Male; D018727:Muscarinic Antagonists / Q000494:pharmacology*; D009206:Myocardium / Q000378:metabolism
D005609:Free Radicals; D018727:Muscarinic Antagonists; D004317:Doxorubicin