title: Heart injury in the calcium paradox: the effect of manganese.
abstract: Prevention by manganese ions of heart injury induced by the calcium paradox was studied in isolated perfused rat heart. Lactate dehydrogenase (LDH) release, ATP and glycogen content, and 45Ca2+ accumulation were used as markers of the injury. If Mn2+ substituted Ca2+ in the perfusion buffer after Ca2+-free perfusion, LDH release from the heart was inhibited but the inhibition was eliminated by Ca2+ readmission. However, Mn2+ (0.2-2.5 mM), added from the beginning of Ca2+-free perfusion, prevented heart injury at the time of Ca2+ repletion. LDH release and 45Ca2+ accumulation in the myocardium were reduced by 90-99%; ATP, glycogen and water content in the heart as well as perfusion pressure and heart rate remained within control values. The observed protective effect of Mn2+ was proportional to its concentration, and to the duration of Ca2+-free perfusion. A possible explanation for the protective effect of Mn2+ ions can be competition with Ca2+ binding sites related to sarcolemma integrity.
authors.affiliation: Institute for Clinical and Experimental Medicine, Cardiovascular Research Programme, Prague, Czechoslovakia.
authors.forename: M
authors.initials: M
authors.lastname: Tutterová
authors.forename: B
authors.initials: B
authors.lastname: Mosinger
authors.forename: H
authors.initials: H
authors.lastname: Vavrínková
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000008:administration & dosage* / Q000378:metabolism; D002132:Calcium Radioisotopes; D006003:Glycogen / Q000378:metabolism; D006331:Heart Diseases / Q000209:etiology* / Q000378:metabolism / Q000517:prevention & control; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008297:Male; D008345:Manganese / Q000627:therapeutic use*; D009206:Myocardium / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D012508:Sarcolemma / Q000378:metabolism
chemical_list: D002132:Calcium Radioisotopes; D008345:Manganese; D000255:Adenosine Triphosphate; D006003:Glycogen; D007770:L-Lactate Dehydrogenase; D002118:Calcium