TC-99M-MIBI UPTAKE IN GREEN PLANTS

Uptake of 99mTc(m)-sestamibi by biological structures depends on deliv ery and concentration by electrochemical gradients through the biologi cal membranes and can be simply studied using a green plant model in w hich photosynthesis tightly modulates water and solute regional flow. Photosynthesis creates electrochemical gradients inside chloroplasts a nd mitochondria. Moreover, it is the driving force for the movement of water and solutes through induction of pore opening which causes capt ure of CO2 and loss of water vapour. Thus osmotic pressure increases t hereby drawing water from the roots. Hypoestes sanguinolenta was used as an experimental model. This plant displays green zones (with severa l chloroplasts) and red zones (where they are absent). To detect the u ptake differences between these zones we used a new, high-resolution g amma camera. Our results show that (a) Tc-99m(m)-sestamibi is actively transported with water and ions by xylem to leaves where it may diffu se at cellular level; (b) activation of photosynthesis by light strong ly influences the total uptake and the selective compartmentation in g reen zones; and (c) the green plant's particular physiology tremendous ly enhances the differences between Tc-99m(m)-sestamibi and Tl-201 upt ake. We suggest that viable cells, able to create and maintain electro chemical gradients, selectively take up Tc-99m-sestamibi.