STUDY OF THE MEMBRANE-PERMEABILITY OF A PARAMAGNETIC METAL-COMPLEX ONSINGLE CELLS BY NMR MICROSCOPY

A new procedure has been developed f or investigating the ability of p aramagnetic metal complexes to penetrate the plasma membrane of eukary otic cells without decomposition. Defolliculated Xenopus laevis oocyte s formed the biological system to test N, N-ethylenebis-(1,5,5- trimet hyltetramic-acid-3-acetiminato) copper (II). An increase of the signal intensities in spin-echo (SE) images of oocytes treated with the test ed substance indicated that the complex was able to penetrate biologic al membranes due to the arrangement of hydrophobic and hydrophilic gro ups within the ligand. In contrast, the treatment with the commonly us ed contrast agent gadolinium-DTPA/dimeglumine did not enhance the sign al intensity in NMR images of oocytes after time periods of exposure c omparable to those used for the copper complex. After microinjection i nto Xenopus oocytes the copper complex was released into the extracell ular medium without degradation, as shown by HPLC measurements.