Cardiac metal contents after infusions of manganese. An experimental evaluation in the isolated rat heart.
OBJECTIVE
Manganese dipyridoxyl diphosphate (MnDPDP), a contrast agent for liver MRI, releases free Mn2+ in a graded manner. The aim of the study was to compare the effects of brief versus prolonged infusions of MnDPDP and manganese chloride (MnCl2) on cardiac function, metabolism, Mn accumulation, and tissue metal content.


METHODS
Isolated perfused rat hearts received 1-minute or 10-minute infusions of MnDPDP (100 microM, 1000 microM) or of MnCl2 (10 microM, 100 microM). Physiologic indices were measured intermittently, and tissue high-energy phosphate compounds and Ca/Fe/Mg/Mn/Zn contents were measured after a standardized Mn washout.


RESULTS
One-minute and 10-minute infusions induced, respectively, minor and marked depressions of contractile function and corresponding elevations in myocardial Mn content. MnCl2 was markedly more potent than MnDPDP. Ten-minute infusions of the highest concentration of MnDPDP and MnCl2 lowered tissue Mg and elevated tissue Ca (MnCl2), whereas high-energy phosphates were unaffected.


CONCLUSIONS
Mn uptake after Mn infusion is strongly related to the duration, concentration, and dose of free Mn ions. Differences in Mn accumulation between MnDPDP and MnCl2 were more pronounced after the 10-minute infusion.
Brurok
H
H
Department of Physiology and Biomedical Engineering, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway.
Berg
K
K
Sneen
L
L
Grant
D
D
Karlsson
J O
JO
Jynge
P
P
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002712:Chlorides / Q000008:administration & dosage / Q000493:pharmacokinetics*; D003287:Contrast Media / Q000008:administration & dosage / Q000493:pharmacokinetics*; D004492:Edetic Acid / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D006321:Heart / Q000187:drug effects* / Q000502:physiology; D066298:In Vitro Techniques; D007501:Iron / Q000378:metabolism; D008274:Magnesium / Q000378:metabolism; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008345:Manganese / Q000378:metabolism*; D017895:Manganese Compounds / Q000008:administration & dosage / Q000493:pharmacokinetics*; D009200:Myocardial Contraction / Q000187:drug effects; D009206:Myocardium / Q000378:metabolism*; D010477:Perfusion; D011732:Pyridoxal Phosphate / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D051381:Rats; D017208:Rats, Wistar; D015032:Zinc / Q000378:metabolism
D002712:Chlorides; D003287:Contrast Media; D017895:Manganese Compounds; D008345:Manganese; D011732:Pyridoxal Phosphate; D004492:Edetic Acid; D007501:Iron; D008274:Magnesium; D015032:Zinc; C060076:N,N'-bis(pyridoxal-5-phosphate)ethylenediamine-N,N'-diacetic acid; C025340:manganese chloride; D002118:Calcium