A bitter substance induces a rise in intracellular calcium in a subpopulation of rat taste cells.

The sense of taste permits animals to discriminate between foods that are safe and those that are toxic. Because most poisonous plant alkaloids are intensely bitter, bitter taste warns animals of potentially hazardous foods. To investigate the mechanism of bitter taste transduction, a preparation of dissociated rat taste cells was developed that can be studied with techniques designed for single-cell measurements. Denatonium, a very bitter substance, caused a rise in the intracellular calcium concentration due to release from internal stores in a small subpopulation of taste cells. Thus, the transduction of bitter taste may occur via a receptor-second messenger mechanism leading to neurotransmitter release and may not involve depolarization-mediated calcium entry.