Caffeine transduction

Cells carefully control the homeostasis of their ion concentrations by the action of ion channels (Na, K , Ca " channels) and throu Na, K -ATPase and Ca -ATPase. These channels and pumps are involved in signal transduction, active transport processes, and neuronal and neuromuscular signaling. Inhibition of transport processes (ion channels, carriers) is achieved by (Table IV) acronycine, ervatamine, harmaline, quinine, reserpine, colchicine, nitidine, salsolinol, sanguinarine, stepholidine, caffeine, sparteine, monocrotaline, steroidal alkaloids, aconitine, capsaicine, cassaine, maitoxin, ochratoxin, palytoxin, pumiliotoxin, saxitoxin, sole-nopsine, and tetrodotoxin. 

In taste studies, sucrose is usually taken as a reference standard in the sensory evaluation of sweetness and caffeine is generally used as the reference material for bitterness. However, sour and salty tastants modulate taste-receptor function by direct effect on specific ion channels in the membrane, while sweet and bitter tasting compounds seem to bind to closely located receptors which are coupled to a guanidine-nucleotide binding protein (G-protein). The perception of their tastes proceeds through a transduction mechanism involving G-protein and a second messenger system (Kinnamon, 1988). 

---