title: Doxorubicin affects the cardiac muscarinic system in the rat.
abstract: During the study on the mechanism of doxorubicin-induced cardiotoxicity, we observed that a long incubation (4 hr) with doxorubicin reduced the maximal negative inotropic effects of a muscarinic receptor agonist, carbachol. The mechanism responsible for this doxorubicin-induced reduction of the efficacy of carbachol was examined in isolated guinea pig hearts. In isolated left atrial muscle preparations, 1 hr incubation with 100 microM doxorubicin caused a parallel right-ward shift of the concentration-response curves for carbachol, but a longer (4 hr) incubation with this agent (30, 100 or 200 microM), caused a significant reduction of the magnitude of the negative inotropic effect of carbachol in addition to the concentration-dependent parallel right-ward shift. The 4-hr incubation with these concentrations of doxorubicin also reduced the maximal negative inotropic effect of an adenosine A1 receptor agonist, R-phenylisopropyl adenosine (R-PIA), without affecting the potency of this agonist. Doxorubicin (1 to 100 microM) reduced [3H]quinuclidinyl benzilate (QNB) binding in a concentration dependent manner, but failed to alter [3HIR-PIA binding. The decrease in the magnitude of the maximal negative inotropic effect by doxorubicin was caused by changes in the muscarinic system at steps common to the transduction of muscarinic and adenosine A1 receptor mechanisms.
authors.affiliation: Department of Veterinary Pharmacology, School of Veterinary Medicine and Animal Sciences, Kitasato University, Towada-shi, Japan
authors.forename: A
authors.initials: A
authors.lastname: Chugun
authors.forename: T
authors.initials: T
authors.lastname: Uchide
authors.forename: K
authors.initials: K
authors.lastname: Temma
authors.forename: R H
authors.initials: RH
authors.lastname: Kennedy
authors.forename: S V
authors.initials: SV
authors.lastname: Klimberg
authors.forename: Y
authors.initials: Y
authors.lastname: Hara
authors.forename: T
authors.initials: T
authors.lastname: Sasaki
authors.forename: T
authors.initials: T
authors.lastname: Akera
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D000970:Antineoplastic Agents / Q000378:metabolism / Q000494:pharmacology* / Q000633:toxicity; D001667:Binding, Competitive; D002217:Carbachol / Q000037:antagonists & inhibitors*; D002316:Cardiotonic Agents / Q000037:antagonists & inhibitors*; D003864:Depression, Chemical; D004317:Doxorubicin / Q000378:metabolism / Q000494:pharmacology* / Q000633:toxicity; D004347:Drug Interactions; D006321:Heart / Q000187:drug effects*; D066298:In Vitro Techniques; D018727:Muscarinic Antagonists / Q000378:metabolism / Q000494:pharmacology* / Q000633:toxicity; D009200:Myocardial Contraction / Q000187:drug effects; D058906:Purinergic P1 Receptor Agonists; D011813:Quinuclidinyl Benzilate / Q000494:pharmacology; D051381:Rats; D011976:Receptors, Muscarinic / Q000378:metabolism*; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D000970:Antineoplastic Agents; D002316:Cardiotonic Agents; D018727:Muscarinic Antagonists; D058906:Purinergic P1 Receptor Agonists; D011976:Receptors, Muscarinic; D014665:Vasodilator Agents; C047235:N-(1-methyl-2-phenylethyl)adenosine; D011813:Quinuclidinyl Benzilate; D004317:Doxorubicin; D002217:Carbachol; D000241:Adenosine