OUR TASTE and IONS Our cells are exquisitely sensitive to changes in the concentration of ions. Ions such as K+, Ca++, Na+. H+ do much of the work of regulating our neurons, our brain cells which transmit messages. For example, in taste cells in our taste buds, hydrogen (H+) ions interact to give an acid taste; sugar activates an enzyme, which closes ion channels to potassium (K+). and bitter stimuli release calcium (Ca++) which leads to neurotransmitter release/ a neuron "firing" off a message to the brain. Chemicals from food dissolve in saliva, and then interact either with ion channel proteins or protein taste receptors. The cells are normally negative within; once they are more positive they release their neurotransmitters. Scientific American March, 2001