Manganese-calcium interactions with contrast media for cardiac magnetic resonance imaging: a study of manganese chloride supplemented with calcium gluconate in isolated Guinea pig hearts.
OBJECTIVE
Manganese ions (Mn) enter cardiomyocytes via calcium (Ca) channels and enhance relaxation intracellularly. To prevent negative inotropy, new Mn-releasing contrast agents have been supplemented with high Ca. The study aim was to investigate how this affects cardiac function and magnetic resonance efficacy.


METHODS
MnCl2 based contrast agents, manganese and manganese-calcium (Ca:Mn 10:1), were infused during 4 repeated washin-washout sequences in perfused guinea pig hearts. [Mn] were 10, 50, 100 and 500 microM.


RESULTS
During washin, manganese depressed left ventricular developed pressure (LVDP) by 4, 9, 17, and 53% whereas manganese-calcium increased LVDP by 13, 18, 25, and 56%. After experiments, tissue Mn contents (nmol/g dry wt) were control <40, manganese 3720, and manganese-calcium 1620. T1 was reduced by 85-92% in Mn-enriched hearts.


CONCLUSIONS
High Ca supplements to Mn-releasing contrast agents may be counterproductive by inducing a strong positive inotropic response and by reducing the magnetic resonance efficacy.
Bruvold
Morten
M
Department of Circulation and Medical Imaging, Faculty of Medicine, Norwegian University of Science and Technology, Medisinsk Teknisk Forskningssenter, Trondheim, Norway.
Nordhøy
Wibeke
W
Anthonsen
Henrik W
HW
Brurok
Heidi
H
Jynge
Per
P
D000255:Adenosine Triphosphate / Q000032:analysis; D000818:Animals; D002118:Calcium / Q000378:metabolism / Q000493:pharmacokinetics*; D002125:Calcium Gluconate / Q000008:administration & dosage / Q000737:chemistry; D002712:Chlorides / Q000008:administration & dosage / Q000737:chemistry / Q000493:pharmacokinetics*; D003287:Contrast Media / Q000737:chemistry / Q000493:pharmacokinetics*; D006168:Guinea Pigs; D006321:Heart / Q000187:drug effects* / Q000502:physiology; D006352:Heart Ventricles / Q000187:drug effects; D008279:Magnetic Resonance Imaging / Q000379:methods; D008345:Manganese / Q000008:administration & dosage / Q000032:analysis / Q000737:chemistry; D017895:Manganese Compounds / Q000008:administration & dosage / Q000737:chemistry / Q000493:pharmacokinetics*; D009200:Myocardial Contraction / Q000187:drug effects; D009206:Myocardium / Q000737:chemistry / Q000378:metabolism; D010477:Perfusion; D010725:Phosphocreatine / Q000032:analysis; D011522:Protons
D002712:Chlorides; D003287:Contrast Media; D017895:Manganese Compounds; D011522:Protons; D010725:Phosphocreatine; D008345:Manganese; D000255:Adenosine Triphosphate; C025340:manganese chloride; D002125:Calcium Gluconate; D002118:Calcium