title: Adenosine A3 receptor-mediated cardioprotection against doxorubicin-induced mitochondrial damage.
abstract: Cardiotoxicity associated with doxorubicin (DOX) treatment limits the therapeutic efficiency of this drug against cancer. 2-Chloro-N(6)-(3-iodobenzyl)adenosine-5'-N-methyluronamide (Cl-IB-MECA), a selective agonist of A(3) adenosine receptor (A(3)R), reduces DOX toxicity in newborn rat cultured cardiomyocytes. The study's aim was to determine whether the protection demonstrated by Cl-IB-MECA attenuates cardiac depression in vivo. In addition, we wished to examine whether this protective pathway affects the sarcoplasmic reticulum (SR) calcium uptake and release, as well as intramitochondrial Ca(2+) accumulation induced by DOX. Rats were injected every alternate day (6 times) with (1) saline, (2) 2.5mg/kg i.p. DOX, (3) 33 microg/kg i.v. Cl-IB-MECA, (4) DOX+Cl-IB-MECA. Left ventricular functions were assessed by invasive (pressure) and non-invasive (echocardiography) techniques at the end of the injection period and 4 weeks later. Cytosolic and intramitochondrial calcium levels were measured with indo-1 and rhod-2 probes. SR Ca(2+) content was determined by exposing cultured rat cardiomyocytes to caffeine. Echocardiography data demonstrate left ventricular wall thinning (23%), an increase in the end systolic dimension (170%) and decreased fractional shortening (35+/-5% vs. 54+/-5%, p<0.01) in DOX-treated animals, compared to the control group. DOX increased Ca(2+) levels in the cytosol and in mitochondria by diminishing the SR Ca(2+) uptake. Pretreatment with Cl-IB-MECA attenuated left ventricular dysfunction, improved SR calcium storage capacity and prevented mitochondrial Ca(2+) overload. We conclude that the adenosine A(3) receptor agonist is effective in vivo against DOX cardiotoxicity via the restoration of Ca(2+) homeostasis and prevention of mitochondrial damage that occurs as a result of Ca(2+) overload.
authors.affiliation: Gonda (Goldschmied) Medical Diagnostic Research Center, The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel.
authors.forename: Avishag K
authors.initials: AK
authors.lastname: Emanuelov
authors.forename: Asher
authors.initials: A
authors.lastname: Shainberg
authors.forename: Yelena
authors.initials: Y
authors.lastname: Chepurko
authors.forename: Doron
authors.initials: D
authors.lastname: Kaplan
authors.forename: Alex
authors.initials: A
authors.lastname: Sagie
authors.forename: Eyal
authors.initials: E
authors.lastname: Porat
authors.forename: Michael
authors.initials: M
authors.lastname: Arad
authors.forename: Edith
authors.initials: E
authors.lastname: Hochhauser
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D000970:Antineoplastic Agents / Q000009:adverse effects / Q000494:pharmacology*; D002478:Cells, Cultured; D004317:Doxorubicin / Q000009:adverse effects / Q000494:pharmacology*; D008297:Male; D008928:Mitochondria / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D043684:Receptor, Adenosine A3 / Q000502:physiology*
chemical_list: D000970:Antineoplastic Agents; D043684:Receptor, Adenosine A3; D004317:Doxorubicin