mechanisms of localization

radpharm test

Capillary Blockade

radiolabeled particles are lodged within capillary beds and occlude them

Active Transport

Isotope using the same metabolic process normally occuring

Phagocytosis

mechanism uses body's process for removing waste to entrap the pharmaceutical
A colloidal material is injected (Tc-99m Sulfur Colloid), trapped by bodies of RES system and phagocytized

Reticuloendothelial SystemR.E.S.

R.E.S.

-85% goes to Kupffer cells in the liver
-10% goes to the R.E.S in the spleen
-5% goes to the R.E.S. in the bone marrow

Cell Sequestration

spleen will concentrate damaged blood cells and repair them, biologic process called (sequestration)

Simple/ Passive Diffusion

RPx will diffuse across cell membranes and redistribute from H to L concentrations

Compartmental localization

Similar to passive diffusion but,
RPx is contained within a confined space where it will diffuse and fill the space

Chemical bonding/ Absorption/ Chemisorption

Bone is made out of hydroxyapatite crystals which are rich in calcium and phosphorous
Phosphorous rich RPx will bind to this crystal structure of growing/remodeling bone

Antigen Antibody Binding

Foreign substance recognized by its surface features called antigens
WBC develop antibodies to fit Lock and Key to each antigen to destroy the intruder

Receptor binding

Surface of cells have specialized membrane protiens which communicate and trigger changes within a cell
Hormones can bind and cause metabolic changes