In vivo animal demonstration of the effect of vasoactive drugs using 195mAu and gamma camera techniques.

195mAu, an ultrashort-lived (physical half life = 30.5 s) generator-produced radionuclide, has been used in an animal model to study, by gamma camera techniques, the peripheral effects of the vasoactive drugs norepinephrine and sodium nitroprusside systemically administered or epinephrine (intraarterially) injected at various concentrations. According to the results obtained by the analysis of time activity curves generated from areas of interest drawn on the proximal and distal parts of the limbs, the well known hemodynamic changes induced by these drugs, vasoconstriction (resulting in a decrease of the distal activity recorded), or vasodilatation (shortening the time of radioactivity appearance), could be observed. It is concluded that gamma camera techniques using the ultrashort lived radionuclide 195mAu allow the in vivo study of the effects of vasoactive drugs in an animal model and potentially in clinical situations.