Dynamic evaluation of the hepatic uptake and clearance of manganese-based MRI contrast agents: A 31P NMR study on the isolated and perfused rat liver

✍ Scribed by Jean-Marie Colet; Luce Vander Elst; Robert N. Muller

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 681 KB
• Volume: 8
• Category: Article
• ISSN: 1053-1807
• DOI: 10.1002/jmri.1880080322

✦ Synopsis

Abstract

This spectroscopic study compares the mechanisms of the hepatic uptake of manganese chloride (MnCl~2~) and manganese dipyridoxyl diphosphate (MnDPDP). Alterations of the phosphorus‐31 (^31^P)‐NMR spectrum of the intracellular adenosine 5′‐triphosphate (ATP) are used to monitor the internalization of manganese by the isolated and perfused rat liver. Mn^2+^ delivered as MnCl~2~ in the perfusate rapidly enters the hepatocytes, where it strongly interacts with ATP, inducing a broadening of the ^31^P lines. The inhibition of the process by nifedipine confirms that manganese ions cross the cellular membrane at least partly through Ca^2+^ channels. MnDPDP induces weaker but still significant changes of the ATP spectrum. The inability of pyridoxine to compete for the uptake of manganese confirms that the vitamin B~6~ carrier is not involved in the internalization process of the paramagnetic complex. Finally, preincubation of MnDPDP with blood does not increase the extent of the dissociation. The alterations of the ^31^P spectrum of the liver subsequent to the administration of MnDPDP are attributable to a fraction of free Mn^2+^ released by the chelate and delivered to the hepatocytes.