99Tcm-MIBI uptake in green plants.

Uptake of 99mTcm-sestamibi by biological structures depends on delivery and concentration by electrochemical gradients through the biological membranes and can be simply studied using a green plant model in which photosynthesis tightly modulates water and solute regional flow. Photosynthesis creates electrochemical gradients inside chloroplasts and mitochondria. Moreover, it is the driving force for the movement of water and solutes through induction of pore opening which causes capture of CO2 and loss of water vapour. Thus osmotic pressure increases thereby drawing water from the roots. Hypoestes sanguinolenta was used as an experimental model. This plant displays green zones (with several chloroplasts) and red zones (where they are absent). To detect the uptake differences between these zones we used a new, high-resolution gamma camera. Our results show that (a) 99mTcm-sestamibi is actively transported with water and ions by xylem to leaves where it may diffuse at cellular levels; (b) activation of photosynthesis by light strongly influences the total uptake and the selective compartmentation in green zones; and (c) the green plant's particular physiology tremendously enhances the differences between 99Tcm-sestamibi and 201Tl uptake. We suggest that viable cells, able to create and maintain electrochemical gradients, selectively take up 99Tcm-sestamibi.