TIME-DIFFERENTIAL PAC PARAMETERS FOR IN-111-DTPA LABELED VESICLES

The perturbed angular correlation of gamma-rays from labelled phosphol ipid vesicles has been found to be caused by approximately equal contr ibutions from static and time-dependent effects. A comparison between the PAC parameters from the labelled vesicular system and the labelled DTPA reporter molecule alone suggests that the PAC nuclide is located within, and not on, the bilayer wall. When the vesicles are lysed wit h triton detergent, there appears to be a reduction in the time-depend ent electric quadrupole field gradient seen by the PAC nuclide but no significant reduction in the size of the bilayer fragments.