For example, small molecules such as NaCl and HCl can directly pass through ion channels. Increases in sodium concentrations can lead to increased sodium conductance through an amiloride-sensitive sodium channel. Other chemicals may activate or block ion channels directly, or bind to receptors similar to G protein-coupled receptors. Sugars and bitter substances can activate receptors coupled to intracellular second messengers such as phosphoinositide hydrolysis. Today, MSG is produced in the United States from sugar beet molasses, in a fermentation process similar to that used in making yeast and sauerkraut.
Glutamic acid is one of the amino acids which make up proteins.
When pure, manufactured, MSG is given, a rapid effect occurs from the glutamate. The sudden increase in glutamic acid within the body is rapidly absorbed an can raise the normal blood levels of glutamate to eight or ten times the usual amount. These are several theories on how MSG, an enhancer, works. It has also been observed that MSG produces certain feelings of sensation in the mouth. Analzying the information collected there only seems to be a correlation of MSG with sweet and salty aspects of taste.